{ "dataset": "U.S. Septic Tank Minimum Size by Bedroom Count and State Regulation", "version": "2026.1", "last_verified": "2026-07-20", "publisher": "Greenville Septic Repairs", "coverage": "50 U.S. states", "units": "gallons (minimum septic tank liquid capacity)", "scope": "Conventional single-family gravity systems. Excludes drainfield sizing, aerobic/mound/pumped systems, commercial systems, and permit approval.", "verification_note": "15 states (and the Arkansas hold) were read directly against the cited primary code; the remaining states are compiled from the cited primary source and are being independently re-verified. Every row links its source.", "provenance_codes": { "A": "Direct statewide schedule", "A*": "Direct schedule verified for part of the 1-6 BR range", "A/B": "Direct schedule combined with a formula", "B": "Formula-derived statewide baseline", "B*": "Permit-specific calculation; not an off-the-shelf tank recommendation", "C": "No single statewide bedroom figure; framework and/or local authority controls", "E": "Verification hold; no numeric answer" }, "attribution": "Compiled from the cited state primary sources; verify against the linked source.", "states": [ { "state": "Alabama", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; permit/site design can require more", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal for each bedroom over 5", "design_flow_gpd_per_bedroom": null, "rule_citation": "Ala. Admin. Code r. 420-3-1-.17", "source_url": "https://admincode.legislature.state.al.us/api/rule/420-3-1-.17", "source_type": "Current administrative rule", "effective_or_current_date": "2023-02-13", "derivation": "Copied directly from official bedroom schedule", "override_flags": "Site-specific permit/design; nonresidential sizing is separate", "notes": "The official table jumps from 1,000 gallons for 1-4 bedrooms to 1,500 gallons for 5 bedrooms, then adds 250 gallons per bedroom over 5.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Alaska", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; DEC approval controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": 150, "rule_citation": "18 AAC 72, residential septic-tank sizing table", "source_url": "https://dec.alaska.gov/media/k3zjcdo4/18-aac-72.pdf", "source_type": "Current administrative code PDF", "effective_or_current_date": "Current register checked 2026-07-20", "derivation": "Copied directly from official bedroom schedule", "override_flags": "Alternative systems and nonresidential uses follow separate design provisions", "notes": "Residential design flow is 150 gallons per day per bedroom in the cited rule set.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Arizona", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule with fixture override", "control_level": "Statewide minimum; county/permit review may be stricter", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 2000, "increment_or_formula": "No single increment; fixture-count thresholds change the result", "design_flow_gpd_per_bedroom": 150, "rule_citation": "Ariz. Admin. Code R18-9-A314, Table 1", "source_url": "https://apps.azsos.gov/public_services/title_18/18-09.pdf", "source_type": "Current administrative code PDF", "effective_or_current_date": "2023-06-19; current PDF checked 2026-07-20", "derivation": "Lower value copied from each bedroom row in the official bedroom-and-fixture table", "override_flags": "Plumbing fixture count; design flow; site-specific approval", "notes": "The displayed values are the lower bedroom-only baseline. Fixture-count thresholds can raise the required capacity: 1 bedroom >7 fixtures; 2 >14; 3 >21; 4 >28; 5 >35; 6 >42.", "confidence": "High", "publication_status": "Publishable with override warning", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Arkansas", "verification_tier": "Verified - read directly against primary code", "provenance_code": "E", "status": "E - Verification hold", "control_level": "State rule contains a conflicting table; authorized agent confirmation required", "bed1": null, "bed2": null, "bed3": null, "bed4": null, "bed5": null, "bed6": null, "increment_or_formula": null, "design_flow_gpd_per_bedroom": null, "rule_citation": "Ark. Rules Pertaining to Onsite Wastewater Systems (2024); ADH guidance", "source_url": "https://healthy.arkansas.gov/wp-content/uploads/Onsite_Wastewater_Rule.pdf", "source_type": "Current official rule PDF", "effective_or_current_date": "2024", "derivation": "No unique value - current sources conflict", "override_flags": "Single-compartment dosing adds at least 250 gallons; authorized agent controls", "notes": "Verification hold: Arkansas's current onsite-wastewater materials do not yield a single consistent bedroom schedule. ADH installer/rules guidance lists 1,000 gal for 1-3 BR and 1,250 at 4, while the ADH alternative-systems manual (Rule 007.04.93-005) lists 1,250 at 3-4 BR. Because the controlling source does not support a unique value, no Arkansas bedroom figure is published. Confirm with ADH or its Authorized Agent.", "confidence": "Verified that current sources conflict at 3 BR (1,000 vs 1,250)", "publication_status": "Hold - do not publish a numeric value", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": null, "highest_bedroom_at_or_below_1500": null }, { "state": "California", "verification_tier": "Verified - read directly against primary code", "provenance_code": "C", "status": "C - No single statewide bedroom figure", "control_level": "Statewide framework + local agency control", "bed1": null, "bed2": null, "bed3": null, "bed4": null, "bed5": null, "bed6": null, "increment_or_formula": null, "design_flow_gpd_per_bedroom": null, "rule_citation": "California Plumbing Code (Title 24) Appendix H; State Water Board OWTS Policy", "source_url": "https://www.waterboards.ca.gov/water_issues/programs/owts/owts_policy.html", "source_type": "Official state policy and program page", "effective_or_current_date": "Policy amended 2023", "derivation": "No single statewide numeric result", "override_flags": "Local LAMP, county code, project flow, treatment type", "notes": "No single statewide bedroom schedule. The California Plumbing Code Appendix H (Private Sewage Disposal Systems) sets statewide sizing provisions, but the State Water Board OWTS Policy lets approved Local Agency Management Programs use different standards, and local agencies commonly set the binding requirement. ~1.2 million OWTS statewide. Confirm with the local agency.", "confidence": "High", "publication_status": "Publishable as no-single-statewide-number status", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": null, "highest_bedroom_at_or_below_1500": null }, { "state": "Colorado", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide schedule; local public health agencies permit and may be stricter", "bed1": null, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per additional bedroom after 4; table starts at 2 bedrooms", "design_flow_gpd_per_bedroom": null, "rule_citation": "5 CCR 1002-43.9, Table 9-1", "source_url": "https://regulations.justia.com/states/colorado/1000/1002/rule-5-ccr-1002-43/section-5-ccr-1002-43-9", "source_type": "Official state program page", "effective_or_current_date": "Current program checked 2026-07-20", "derivation": "Copied from Table 9-1", "override_flags": "County OWTS regulation, design flow, treatment type", "notes": "Table 9-1: 2-3 BR=1,000; 4=1,250; +250 each additional. Table starts at 2 bedrooms (no 1-BR value specified). Low-flow fixtures do not reduce sizing; certain treatment configurations may allow <1,000 gal with 48-hr detention.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Connecticut", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide technical standard; local health approval still required", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1125, "bed5": 1250, "bed6": 1375, "increment_or_formula": "125 gal per bedroom over 3", "design_flow_gpd_per_bedroom": 150, "rule_citation": "Connecticut Technical Standards for Subsurface Sewage Disposal Systems (2024), residential tank table", "source_url": "https://portal.ct.gov/dph/-/media/dph/dph-2025/environmental-engineering-program/subsurface-sewage/guidance-and-design-resources/technical-standards-for-subsurface-sewage-disposal-systems-rev-2024.pdf?rev=d7bfe1e32b7440b0a737834ce8caf86e", "source_type": "Current official technical standards PDF", "effective_or_current_date": "2024-01-01", "derivation": "Copied directly from official schedule", "override_flags": "Special wastewater characteristics and engineered designs", "notes": "The schedule uses a 1,000-gallon minimum through 3 bedrooms and adds 125 gallons for each additional bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Delaware", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "B", "status": "B - Formula-derived statewide baseline", "control_level": "Statewide formula; DNREC permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1500, "bed6": 1500, "increment_or_formula": "For design flow >500 and <2,500 gpd: 1.5x design flow, minimum 1,500 gal", "design_flow_gpd_per_bedroom": 120, "rule_citation": "7 Del. Admin. Code 7101, residential flow and septic-tank sizing provisions", "source_url": "https://dnrec.delaware.gov/water/residential/septic-systems/", "source_type": "Official DNREC rule hub and linked regulation", "effective_or_current_date": "Current rules linked by DNREC; checked 2026-07-20", "derivation": "Calculated from official residential flow and tank-capacity formula", "override_flags": "Actual/engineered flow, nonresidential use, treatment configuration", "notes": "Residential flow is 120 gpd per bedroom with a 240-gpd minimum. A tank is 1,000 gallons at design flows up to 500 gpd; above 500 and below 2,500 gpd the rule uses 1.5 times flow with a 1,500-gallon minimum.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Florida", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "B", "status": "B - Formula-derived statewide baseline with floor-area override", "control_level": "Statewide tables; county health department permit controls", "bed1": 900, "bed2": 900, "bed3": 900, "bed4": 1050, "bed5": 1200, "bed6": 1350, "increment_or_formula": "Flow and capacity table; no single bedroom increment", "design_flow_gpd_per_bedroom": null, "rule_citation": "Fla. Admin. Code r. 62-6.008, Tables I and II", "source_url": "https://flrules.org/gateway/ruleno.asp?id=62-6.008", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Calculated by pairing official residential design-flow Table I with official tank Table II", "override_flags": "Heated/cooled floor area; actual use; nonresidential flow; special fixtures", "notes": "These are bedroom-only baselines using the minimum floor-area band for each bedroom count. Florida uses the greater result from bedroom count and floor area, then maps design flow to the official tank-capacity table.", "confidence": "High", "publication_status": "Publishable with floor-area warning", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Georgia", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide manual; county environmental health permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": null, "rule_citation": "Georgia DPH Manual for On-Site Sewage Management Systems, Section A", "source_url": "https://dph.georgia.gov/document/document/envhealthonsitemanual2024-02-22sectionapdf/download", "source_type": "Current official state manual", "effective_or_current_date": "2024 manual checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Garbage grinder +50%; nonresidential and engineered designs", "notes": "A garbage grinder increases the scheduled septic-tank capacity by 50 percent under the cited manual.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Hawaii", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A/B", "status": "A/B - Direct schedule plus formula", "control_level": "Statewide minimum; Department of Health approval controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "For >5 bedrooms: 1000 + (Q - 800) x 1.25", "design_flow_gpd_per_bedroom": 200, "rule_citation": "Hawaii Administrative Rules, Chapter 11-62, wastewater system sizing provisions", "source_url": "https://health.hawaii.gov/wastewater/home/rule/", "source_type": "Official state rule hub and rule text", "effective_or_current_date": "Current rule hub checked 2026-07-20", "derivation": "Direct values through 5 bedrooms; 6-bedroom value calculated from official formula", "override_flags": "Actual design flow and nonresidential use", "notes": "The rule provides 1,000 gallons through 4 bedrooms, 1,250 for 5, and a formula above 5 using 200 gpd per bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Idaho", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; district health department permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": null, "rule_citation": "IDAPA 58.01.03, Individual/Subsurface Sewage Disposal Rules", "source_url": "https://adminrules.idaho.gov/rules/current/58/580103.pdf", "source_type": "Current administrative rule PDF", "effective_or_current_date": "2025-07-01", "derivation": "Copied directly from official schedule", "override_flags": "Site-specific design and nonresidential flow", "notes": "The current Idaho rule uses a 1,000-gallon minimum through 4 bedrooms and adds 250 gallons for each additional bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Illinois", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local health department permit controls", "bed1": 750, "bed2": 750, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": null, "rule_citation": "77 Ill. Adm. Code Part 905, septic-tank capacity table", "source_url": "https://www.ilga.gov/agencies/JCAR/EntirePart?titlepart=07700905", "source_type": "Current administrative code", "effective_or_current_date": "Current code checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Garbage grinder schedule; engineered/nonresidential use", "notes": "The schedule is 750 gallons for 1-2 bedrooms, 1,000 for 3, then +250 per bedroom. A separate larger schedule applies when a garbage grinder is installed.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Indiana", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide rule; local health department permit controls", "bed1": 750, "bed2": 750, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1800, "increment_or_formula": "300 gal per bedroom over 5", "design_flow_gpd_per_bedroom": 150, "rule_citation": "410 IAC 6-8.3 (current rule effective 2024), septic-tank sizing table", "source_url": "https://www.in.gov/health/eph/onsite-sewage-systems-program/historic-bulletins-and-rules/", "source_type": "Official state rule hub and current rule", "effective_or_current_date": "2024-03-28", "derivation": "Copied directly from current official schedule", "override_flags": "Pending rulemaking; nonresidential and alternative systems", "notes": "Indiana's current table uses 1,800 gallons at 6 bedrooms and adds 300 gallons for each bedroom over 5. A proposed revision was not treated as effective.", "confidence": "High", "publication_status": "Publishable; monitor rulemaking", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Iowa", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; county permitting may be more restrictive", "bed1": 1250, "bed2": 1250, "bed3": 1250, "bed4": 1500, "bed5": 1750, "bed6": 2000, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": null, "rule_citation": "Iowa Admin. Code ch. 567-69, septic-tank capacity table", "source_url": "https://www.legis.iowa.gov/docs/ACO/chapter/567.69.pdf", "source_type": "Current administrative code PDF", "effective_or_current_date": "2025-09-10", "derivation": "Copied directly from official schedule", "override_flags": "Local requirements and special designs", "notes": "Iowa uses a 1,250-gallon minimum through 3 bedrooms and adds 250 gallons per additional bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": null, "highest_bedroom_at_or_below_1500": 4 }, { "state": "Kansas", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "B", "status": "B - Formula-derived statewide minimum standard", "control_level": "State minimum standard; local authority/permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1200, "bed5": 1500, "bed6": 1800, "increment_or_formula": "Tank >= 2x design flow, minimum 1,000 gal", "design_flow_gpd_per_bedroom": 150, "rule_citation": "KDHE Bulletin 4-2, Minimum Standards for Design and Construction of Onsite Wastewater Systems", "source_url": "https://www.kdhe.ks.gov/DocumentCenter/View/8770/Bulletin-4-2-Minimum-Standards-for-Design-and-Construction-of-Onsite-Wastewater-Systems-PDF", "source_type": "Official state design standard", "effective_or_current_date": "Current bulletin checked 2026-07-20", "derivation": "Calculated from official flow and capacity formula", "override_flags": "Garbage disposal uses 3x flow; actual/nonresidential flow", "notes": "Values are calculated from 150 gpd per bedroom and a minimum tank volume of twice daily flow, with a 1,000-gallon floor. A garbage disposal changes the factor to three times design flow.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Kentucky", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local health department approval controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": 110, "rule_citation": "902 KAR 10:085, septic-tank capacity table", "source_url": "https://apps.legislature.ky.gov/law/kar/titles/902/010/085/", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied from official no-disposal schedule", "override_flags": "Garbage disposal schedule; nonresidential flow", "notes": "Displayed values are for dwellings without a garbage disposal. With a disposal, the rule's schedule is 1,250 gallons through 3 bedrooms, then 1,500, 1,750, and 2,000 gallons for 4-6 bedrooms.", "confidence": "High", "publication_status": "Publishable with disposal toggle", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Louisiana", "verification_tier": "Verified - read directly against primary code", "provenance_code": "B", "status": "B - Formula-derived statewide baseline", "control_level": "Statewide official design guidance; parish/LDH approval controls", "bed1": 500, "bed2": 750, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "2.5x official average daily flow; 500-gal minimum for 1 bedroom", "design_flow_gpd_per_bedroom": null, "rule_citation": "La. Admin. Code tit. 51, Sec. XIII-715", "source_url": "https://www.law.cornell.edu/regulations/louisiana/La-Admin-Code-tit-51-SS-XIII-715", "source_type": "Official agency training/design material", "effective_or_current_date": "Current official material checked 2026-07-20", "derivation": "Calculated from official residential-flow table and 2.5x formula", "override_flags": "Actual use, high-strength waste, treatment type", "notes": "Capacity = 2.5x estimated average daily design flow. A 1-bedroom residence may use a 500-gal tank; 500 gal is the floor for all applications. Values above 1 BR are formula-derived.", "confidence": "High for 1-BR floor and formula", "publication_status": "Publishable with calculated-value label", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Maine", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local plumbing inspector approval controls", "bed1": 750, "bed2": 750, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4/according to schedule", "design_flow_gpd_per_bedroom": null, "rule_citation": "10-144 CMR Chapter 241, Maine Subsurface Wastewater Disposal Rules", "source_url": "https://www.maine.gov/sos/sites/maine.gov.sos/files/inline-files/144c241-2023-172%20%28AMD%29.docx", "source_type": "Current official rule document", "effective_or_current_date": "Current amended rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Garbage disposal/treatment configuration may require additional capacity; verify current local application", "notes": "The official schedule is 750 gallons for 1-2 bedrooms, 1,000 for 3-4, 1,250 for 5, and 1,500 for 6.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Maryland", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; county environmental health approval controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": 150, "rule_citation": "COMAR 26.04.02.05", "source_url": "https://regs.maryland.gov/us/md/exec/comar/26.04.02.05", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Actual flow and engineered/nonresidential designs", "notes": "Maryland uses 1,000 gallons through 3 bedrooms and adds 250 gallons for each additional bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Massachusetts", "verification_tier": "Verified - read directly against primary code", "provenance_code": "B", "status": "B - Formula-derived statewide baseline", "control_level": "Statewide minimum; local board of health may be stricter", "bed1": 1500, "bed2": 1500, "bed3": 1500, "bed4": 1500, "bed5": 1500, "bed6": 1500, "increment_or_formula": "Greater of 200% design flow, 48-hour flow, or 1,500 gal minimum", "design_flow_gpd_per_bedroom": 110, "rule_citation": "310 CMR 15.223 and Title 5 design-flow provisions", "source_url": "https://www.mass.gov/regulations/310-CMR-15000-septic-systems-title-5", "source_type": "Current regulation and official FAQ", "effective_or_current_date": "Current regulation checked 2026-07-20", "derivation": "Calculated from official flow rule and 1,500-gallon minimum", "override_flags": "Local board requirements; design flow; nonresidential use", "notes": "310 CMR 15.223(a): greater of 200% of design flow or 48-hour detention, with a 1,500-gal minimum (single-family, <1,000 gpd). At 110 gpd/BR the 1,500-gal floor controls through 6 BR; a 7-BR home computes ~1,540 gal. A garbage grinder increases the minimum.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": null, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Michigan", "verification_tier": "Verified - read directly against primary code", "provenance_code": "C", "status": "C - Local/AHJ control", "control_level": "Local health department sanitary code controls", "bed1": null, "bed2": null, "bed3": null, "bed4": null, "bed5": null, "bed6": null, "increment_or_formula": null, "design_flow_gpd_per_bedroom": null, "rule_citation": "Michigan Criteria for Subsurface Sewage Disposal; local sanitary codes", "source_url": "https://www.michigan.gov/-/media/Project/Websites/egle/Documents/Programs/DWEHD/Onsite-Wastewater-Management/Michigan-Criteria-Subsurface-Sewage-Disposal.pdf", "source_type": "Official state criteria explaining local governance", "effective_or_current_date": "Current program material checked 2026-07-20", "derivation": "No single statewide numeric result published", "override_flags": "County/district health code and permit design", "notes": "Only U.S. state with no statewide septic sanitary code (as of 2026). As of early 2026, about 12 of 83 counties have local septic ordinances. ~1.3 million systems statewide, an estimated 300,000+ failing. SB 771 (introduced Jan 2026) would create a first-ever statewide code; pending in the Senate, not yet law as of last review.", "confidence": "High", "publication_status": "Publishable as local-control status", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": null, "highest_bedroom_at_or_below_1500": null }, { "state": "Minnesota", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local permitting authority controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1500, "bed5": 1500, "bed6": 2000, "increment_or_formula": "Schedule bands: <=3, 4-5, 6-7, 8-9 bedrooms", "design_flow_gpd_per_bedroom": null, "rule_citation": "Minn. R. 7080.1930", "source_url": "https://www.revisor.mn.gov/rules/7080.1930/", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Garbage disposal or sewage pump +50%; engineered uses", "notes": "Minnesota's schedule is 1,000 gallons through 3 bedrooms, 1,500 for 4-5, and 2,000 for 6-7. A garbage disposal or sewage pump increases capacity by 50 percent.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Mississippi", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule with equipment branch", "control_level": "Statewide schedule; county/MSDH permit controls", "bed1": 750, "bed2": 750, "bed3": 900, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "260 gal per extra bedroom beyond schedule; occupancy adjustment also applies", "design_flow_gpd_per_bedroom": null, "rule_citation": "Mississippi State Department of Health onsite wastewater regulations, residential septic-tank table", "source_url": "https://msdh.ms.gov/page/resources/21909.pdf", "source_type": "Official state regulation PDF", "effective_or_current_date": "Current official PDF checked 2026-07-20", "derivation": "Copied from the official outlet-baffle/filter branch", "override_flags": "Outlet baffle/filter branch; +260 per extra bedroom; +130 per occupant above 2 per bedroom", "notes": "Displayed values use the branch with an approved outlet baffle/filter. Without that device the official schedule is 750, 750, 900, 1,200, 1,500, and 1,800 gallons for 1-6 bedrooms. Occupancy above two persons per bedroom adds capacity.", "confidence": "High", "publication_status": "Publishable with branch selector", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Missouri", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A*", "status": "A* - Direct statewide schedule through 5 bedrooms", "control_level": "State standards with local administrative authority", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": null, "increment_or_formula": "250 gal per bedroom for 4-5; 6+ requires formula/site design", "design_flow_gpd_per_bedroom": null, "rule_citation": "Missouri Department of Health and Senior Services Onsite Wastewater Treatment Systems Reference Book", "source_url": "https://health.mo.gov/living/environment/onsite/pdf/onsite_ref_book.pdf", "source_type": "Official state reference manual", "effective_or_current_date": "Current official reference checked 2026-07-20", "derivation": "Direct schedule through 5; no invented 6-bedroom value", "override_flags": "6+ bedroom design flow; local authority; nonresidential use", "notes": "The official schedule directly states 1,000 gallons through 3 bedrooms, 1,250 for 4, and 1,500 for 5. For 6 or more bedrooms, use the applicable design-flow/formula and local authority review rather than extending the table.", "confidence": "High for 1-5; Medium for 6+ treatment", "publication_status": "Publishable with 6+ formula/AHJ flag", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Montana", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide standard; reviewing authority permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1500, "bed5": 1500, "bed6": 2000, "increment_or_formula": "Schedule bands: 1-3, 4-5, 6-7 bedrooms", "design_flow_gpd_per_bedroom": null, "rule_citation": "Montana DEQ Circular DEQ-4 (2023), septic-tank sizing table", "source_url": "https://deq.mt.gov/files/Water/WQInfo/Documents/Subdivisions/DEQ-4-2023.pdf", "source_type": "Current official design circular", "effective_or_current_date": "2023", "derivation": "Copied directly from official schedule", "override_flags": "Reviewing authority and engineered systems", "notes": "The schedule is 1,000 gallons for 1-3 bedrooms, 1,500 for 4-5, and 2,000 for 6-7.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Nebraska", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; authorized local program/department permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": null, "rule_citation": "Nebraska Title 124, residential design-flow and septic-tank capacity tables", "source_url": "https://dwee.nebraska.gov/sites/default/files/publications/23-017%20-%20Title%20124%20Onsite%20Wastewater%20Treatment%20Systems%20Booklet.pdf", "source_type": "Current official rule booklet", "effective_or_current_date": "2022-06-27", "derivation": "Copied directly from official baseline capacity table", "override_flags": "Garbage grinder; large tub; pump into single-compartment tank +50%", "notes": "Displayed values are the baseline without a garbage grinder or large tub. The rule has larger values for those features, and pumping into a single-compartment tank can require a 50-percent increase.", "confidence": "High", "publication_status": "Publishable with override flags", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Nevada", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local health authority permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1200, "bed5": 1500, "bed6": 1500, "increment_or_formula": "Schedule bands; +150 gal per bedroom above 8", "design_flow_gpd_per_bedroom": null, "rule_citation": "Nevada Administrative Code, Chapter 444, individual sewage disposal systems", "source_url": "https://www.leg.state.nv.us/nac/nac-444.html", "source_type": "Current administrative code", "effective_or_current_date": "Current code checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Local authority and engineered/nonresidential designs", "notes": "The official schedule is 1,000 gallons through 3 bedrooms, 1,200 for 4, 1,500 for 5-6, and 2,000 for 7-8.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 6 }, { "state": "New Hampshire", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; DES approval controls", "bed1": 1250, "bed2": 1250, "bed3": 1250, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 4 through 10", "design_flow_gpd_per_bedroom": null, "rule_citation": "N.H. Code Admin. R. Env-Wq 1000, residential septic-tank sizing provisions", "source_url": "https://gc.nh.gov/rules/state_agencies/env-wq1000.html", "source_type": "Current administrative rules", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Garbage grinder +50%; pending rulemaking", "notes": "The official schedule uses 1,250 gallons through 4 bedrooms and adds 250 gallons per additional bedroom. A garbage grinder increases capacity by 50 percent. Active rulemaking should be monitored.", "confidence": "High", "publication_status": "Publishable; monitor rulemaking", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": null, "highest_bedroom_at_or_below_1500": 5 }, { "state": "New Jersey", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A/B", "status": "A/B - Direct formula schedule", "control_level": "Statewide minimum; local administrative authority approval controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": null, "rule_citation": "N.J.A.C. 7:9A, septic-tank capacity provisions", "source_url": "https://dep.nj.gov/wp-content/uploads/rules/njac7_9a.pdf", "source_type": "Current administrative code PDF", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Calculated from official per-bedroom formula and minimum", "override_flags": "Garbage grinder or sewage ejector +50%", "notes": "The rule uses 250 gallons per bedroom with a 1,000-gallon minimum. A garbage grinder or sewage ejector increases capacity by 50 percent.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "New Mexico", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; NMED field office permit controls", "bed1": 750, "bed2": 1000, "bed3": 1000, "bed4": 1200, "bed5": 1500, "bed6": 1500, "increment_or_formula": "Schedule bands; 7-9 bedrooms = 2,000 gal", "design_flow_gpd_per_bedroom": null, "rule_citation": "20.7.3.201 NMAC, Table 201.2", "source_url": "https://regulations.justia.com/states/new-mexico/title-20/chapter-7/part-3/section-20-7-3-201", "source_type": "Current official codified rule", "effective_or_current_date": "Current codified rule checked 2026-07-20", "derivation": "Copied directly from official Table 201.2", "override_flags": "Fixture units or design-flow formula where applicable", "notes": "Table 201.2: 1 BR=750; 2-3=1,000; 4=1,200; 5-6=1,500; 7-9=2,000. Or 2.5x design flow, whichever is greater.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 6 }, { "state": "New York", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; county/local health approval controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 6", "design_flow_gpd_per_bedroom": null, "rule_citation": "10 NYCRR Appendix 75-A, septic-tank capacity table", "source_url": "https://www.health.ny.gov/environmental/water/drinking/docs/appendix_75a.pdf", "source_type": "Current official state standard", "effective_or_current_date": "Current official standard checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Local health department requirements and engineered systems", "notes": "10 NYCRR App. 75-A, Table 3: 1-3 BR=1,000; 4=1,250; 5=1,500; 6=1,750; +250/BR over 6. A grinder pump counts as an added bedroom. 110 gpd/BR.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "North Carolina", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A/B", "status": "A/B - Direct minimum through 5; formula above 5", "control_level": "Statewide minimum/formula; local health department permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1342.4, "increment_or_formula": "For >5 bedrooms use official tank-volume formula", "design_flow_gpd_per_bedroom": 120, "rule_citation": "15A NCAC 18E .0801, Table XIV", "source_url": "http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2018%20-%20environmental%20health/subchapter%20e/15a%20ncac%2018e%20.0801.pdf", "source_type": "Current official administrative rule", "effective_or_current_date": "Current codified rule checked 2026-07-20", "derivation": "Direct minimum through 5; 6-bedroom value calculated from official formula and design flow", "override_flags": "Grinder/lift pump before tank DOUBLES required capacity (.0801(c)); design flow 120 gpd/BR", "notes": "Table XIV: 4 BR or fewer=1,000; 5=1,250. 6+ by Rule .0801 formula (~1,342 gal calculated). A grinder or sewage lift pump installed before the tank doubles the required capacity (.0801(c)). 120 gpd/BR.", "confidence": "High through 5; Medium-High for normalized 6-bedroom calculation", "publication_status": "Publishable with calculated-value label", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "North Dakota", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local/state permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1200, "bed5": 1500, "bed6": 1500, "increment_or_formula": "Schedule bands", "design_flow_gpd_per_bedroom": null, "rule_citation": "N.D. Admin. Code ch. 62-03.1-03, residential septic-tank table", "source_url": "https://ndlegis.gov/information/acdata/pdf/62-03.1-03.pdf", "source_type": "Current administrative rule PDF", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Pending rulemaking and engineered systems", "notes": "The current schedule is 1,000 gallons through 3 bedrooms, 1,200 for 4, and 1,500 for 5-6. Proposed 2026 language was not treated as effective.", "confidence": "High", "publication_status": "Publishable; monitor rulemaking", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Ohio", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; board of health permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1500, "bed4": 2000, "bed5": 2000, "bed6": 2500, "increment_or_formula": "250 gal per bedroom above 6", "design_flow_gpd_per_bedroom": null, "rule_citation": "Ohio Admin. Code 3701-29-12", "source_url": "https://codes.ohio.gov/ohio-administrative-code/rule-3701-29-12", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Alternative treatment and nonresidential systems", "notes": "Ohio's schedule is 1,000 gallons for 1-2 bedrooms, 1,500 for 3, 2,000 for 4-5, and 2,500 for 6, with 250 gallons for each bedroom above 6.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 2, "highest_bedroom_at_or_below_1500": 3 }, { "state": "Oklahoma", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; DEQ/local authorization controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": null, "rule_citation": "OAC 252:641-7-2", "source_url": "https://oklahoma.gov/content/dam/ok/en/deq/documents/deqmainresources/641.pdf", "source_type": "Current administrative rule PDF", "effective_or_current_date": "Current official PDF checked 2026-07-20", "derivation": "Copied directly from official rule", "override_flags": "Nonresidential flow and alternative systems", "notes": "The rule provides 1,000 gallons for a residence with four or fewer bedrooms and adds 250 gallons per bedroom above four.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Oregon", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; county/DEQ permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1500, "bed6": 1500, "increment_or_formula": "Schedule bands: <=4 and 5-6 bedrooms", "design_flow_gpd_per_bedroom": null, "rule_citation": "OAR 340-071-0220", "source_url": "https://secure.sos.state.or.us/oard/view.action?ruleNumber=340-071-0220", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Alternative treatment, nonresidential design, local permit conditions", "notes": "The statewide schedule uses 1,000 gallons through 4 bedrooms and 1,500 gallons for 5-6.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Pennsylvania", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "B", "status": "B - Formula-derived statewide baseline", "control_level": "Statewide formula; local sewage enforcement officer/permit controls", "bed1": 900, "bed2": 900, "bed3": 900, "bed4": 1250, "bed5": 1400, "bed6": 1550, "increment_or_formula": "Piecewise tank-capacity formula based on official design flow", "design_flow_gpd_per_bedroom": null, "rule_citation": "25 Pa. Code Chapter 73, design-flow and septic-tank capacity provisions", "source_url": "https://www.pacodeandbulletin.gov/display/pacode?d=reduce&file=%2Fsecure%2Fpacode%2Fdata%2F025%2Fchapter73%2Fchap73toc.html", "source_type": "Current administrative code", "effective_or_current_date": "Current code checked 2026-07-20", "derivation": "Calculated from official residential flow and piecewise capacity formula", "override_flags": "Approved product size; high-strength/nonresidential flow", "notes": "The rule assigns 400 gpd through 3 bedrooms and adds 100 gpd per bedroom above 3. Capacity is 900 + 3.5(flow-400) for 0-500 gpd, then 1,250 + 1.5(flow-500) above 500 gpd. Product/permit sizing may round up.", "confidence": "High", "publication_status": "Publishable with calculated-value label", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Rhode Island", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; DEM permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": null, "rule_citation": "250-RICR-150-10-6, septic-tank sizing provisions", "source_url": "https://rules.sos.ri.gov/regulations/part/250-150-10-6", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Garbage grinder +250; large bathtub +250", "notes": "The rule uses 1,000 gallons through 3 bedrooms and adds 250 gallons per additional bedroom. A garbage grinder or a bathtub of at least 100 gallons adds 250 gallons each.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "South Carolina", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; SCDES permit/site design can require more", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": 120, "rule_citation": "S.C. Code Regs. 61-56 \u00a7201.1(3); SCDES residential design-flow guidance", "source_url": "https://des.sc.gov/sites/des/files/Library/Regulations/R.61-56.pdf", "source_type": "Current state regulation and official guidance", "effective_or_current_date": "2024-07-01", "derivation": "Copied directly from official schedule", "override_flags": "Permit conditions, site design, nonresidential flow", "notes": "Net liquid capacity is 1,000 gallons for a dwelling with four bedrooms or fewer, plus 250 gallons for each bedroom over four. SCDES describes residential design flow as approximately 120 gpd per bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "South Dakota", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; department/local permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": null, "rule_citation": "ARSD Article 74:53, individual and small on-site wastewater systems", "source_url": "https://sdlegislature.gov/Rules/Administrative/74%3A53%3A01", "source_type": "Current administrative rules", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Alternative systems and nonresidential flow", "notes": "South Dakota uses 1,000 gallons through 3 bedrooms and adds 250 gallons per additional bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Tennessee", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; TDEC/local approval controls", "bed1": 750, "bed2": 750, "bed3": 900, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": null, "rule_citation": "Tenn. Comp. R. & Regs. 0400-48, septic-tank capacity schedule", "source_url": "https://publications.tnsosfiles.com/rules/0400/0400-48/0400-48.htm", "source_type": "Current administrative rules", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Alternative systems and nonresidential flow", "notes": "The schedule is 750 gallons for 1-2 bedrooms, 900 for 3, 1,000 for 4, then +250 gallons per bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Texas", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "B", "status": "B - Formula/table-derived statewide baseline with floor-area/water-saving branches", "control_level": "Statewide minimum tables; authorized agent/local authority may be stricter", "bed1": 750, "bed2": 750, "bed3": 1000, "bed4": 1250, "bed5": 1250, "bed6": 1312.5, "increment_or_formula": "Official daily-use table mapped to official capacity table", "design_flow_gpd_per_bedroom": null, "rule_citation": "30 TAC Chapter 285, \u00a7285.32 and Tables II-III", "source_url": "https://www.tceq.texas.gov/downloads/publications/rg/on-site-sewage-facility-rules-compilation-rg-472.pdf/%40%40download/file/rg-472.pdf", "source_type": "Current official rules compilation", "effective_or_current_date": "Current compilation checked 2026-07-20", "derivation": "Mapped official residential daily-use values to official tank-capacity table", "override_flags": "Floor area, water-saving fixtures, actual use, local authority, approved product size", "notes": "Displayed values use the conservative no-water-saving bedroom baseline. Qualifying water-saving fixtures can lower some results; floor area and actual water use can increase them. The 6-bedroom result is the exact formula value 2.5 x 525 gpd and may be rounded up to an approved tank.", "confidence": "High", "publication_status": "Publishable with branch controls", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Utah", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local health department permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1250, "bed5": 1500, "bed6": 1750, "increment_or_formula": "250 gal per bedroom over 3", "design_flow_gpd_per_bedroom": null, "rule_citation": "Utah Admin. Code R317-4, septic-tank sizing table", "source_url": "https://rules.utah.gov/publicat/code/r317/r317-004.htm", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly from official schedule", "override_flags": "Unfinished basement/bedroom potential; regulator discretion", "notes": "Utah uses 1,000 gallons through 3 bedrooms and adds 250 gallons per bedroom. An unfinished basement may be counted as bedroom potential, and the regulator can require more capacity.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Vermont", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "B", "status": "B - Formula-derived statewide baseline", "control_level": "Statewide formula; state permit/design controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1000, "bed6": 1260, "increment_or_formula": "<=560 gpd: 1,000 gal; >560 and <6,500 gpd: 2x design flow", "design_flow_gpd_per_bedroom": 140, "rule_citation": "Vermont Environmental Protection Rules, Wastewater System and Potable Water Supply Rules, Table 9-1", "source_url": "https://semspub.epa.gov/work/01/639155.pdf", "source_type": "Official rule copy plus current agency rulemaking materials", "effective_or_current_date": "Rules effective 2023-11-06; administrative update 2024", "derivation": "Calculated from official minimum bedroom assumption, design flow, and Table 9-1", "override_flags": "Garbage disposal +50%; pump configuration; approved product size", "notes": "Vermont designs a 1-bedroom dwelling as at least 2 bedrooms. At 140 gpd per bedroom, the 1,000-gallon floor controls through 5 bedrooms; 6 bedrooms yields 1,260 gallons. A garbage disposal adds 50 percent, and pumping can increase capacity.", "confidence": "High", "publication_status": "Publishable with calculated-value label", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 5, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Virginia", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A*", "status": "A* - Direct statewide schedule through 5 bedrooms", "control_level": "Statewide rule; local health department permit controls", "bed1": 750, "bed2": 750, "bed3": 900, "bed4": 1200, "bed5": 1500, "bed6": null, "increment_or_formula": "6+ requires design-flow detention calculation/permit review", "design_flow_gpd_per_bedroom": null, "rule_citation": "12VAC5-610-815, Table 5.2", "source_url": "https://law.lis.virginia.gov/admincode/title12/agency5/chapter610/section815/", "source_type": "Current administrative rule", "effective_or_current_date": "Current rule checked 2026-07-20", "derivation": "Copied directly through 5; no invented 6-bedroom value", "override_flags": "6+ design calculation; local health department review", "notes": "Table 5.2 directly gives 750 gallons for 1-2 bedrooms, 900 for 3, 1,200 for 4, and 1,500 for 5. The table stops at 5; do not extrapolate a 6-bedroom value without the controlling design-flow calculation and permit review.", "confidence": "High for 1-5", "publication_status": "Publishable with 6+ design flag", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 3, "highest_bedroom_at_or_below_1500": 5 }, { "state": "Washington", "verification_tier": "Verified - read directly against primary code", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local health jurisdiction permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": 120, "rule_citation": "WAC 246-272A-0232", "source_url": "https://app.leg.wa.gov/wac/default.aspx?cite=246-272A-0232", "source_type": "Current administrative rule", "effective_or_current_date": "2025-04-01", "derivation": "Copied directly from current schedule", "override_flags": "Local health jurisdiction and engineered systems", "notes": "The current schedule is 1,000 gallons through 4 bedrooms, 1,250 for 5, and 1,500 for 6. Older 750/900-gallon charts are superseded.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "West Virginia", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; local health department permit controls", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1250, "bed6": 1500, "increment_or_formula": "250 gal per bedroom over 4", "design_flow_gpd_per_bedroom": null, "rule_citation": "64 CSR 47, residential septic-tank sizing table", "source_url": "https://oehs.wvdhhr.org/media/pz5j11nm/64-csr-47-excerpts-formerly-es-52-updated-2025.pdf", "source_type": "Current official rule excerpt", "effective_or_current_date": "2025-07-01", "derivation": "Copied directly from official schedule", "override_flags": "Alternative/engineered systems and nonresidential flow", "notes": "The 2025 rule uses 1,000 gallons through 4 bedrooms and adds 250 gallons per additional bedroom.", "confidence": "High", "publication_status": "Publishable", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 }, { "state": "Wisconsin", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "B*", "status": "B* - Permit-specific formula; no safe off-the-shelf bedroom chart", "control_level": "State code and county sanitary permit; approved product controls", "bed1": null, "bed2": null, "bed3": null, "bed4": null, "bed5": null, "bed6": null, "increment_or_formula": "Design flow x 2.088 for a 3-year service-cycle calculation", "design_flow_gpd_per_bedroom": 150, "rule_citation": "Wis. Admin. Code SPS 383 and DSPS POWTS Inspector Handbook", "source_url": "https://dsps.wi.gov/Documents/Programs/POWTS/POWTSInspectorHandbook2022.pdf", "source_type": "Current code plus official inspector handbook", "effective_or_current_date": "Current code framework checked 2026-07-20", "derivation": "Calculated from 150 gpd per bedroom and the official 2.088 service-cycle factor", "override_flags": "Department concurrence/maintenance basis; sanitary permit; approved product capacity", "notes": "Formula only: design flow (150 gpd/BR) x 2.088. A 3-BR home computes to ~940 gal, but this is a calculated regulatory minimum, not a stocked or approvable tank size. Actual permitted capacity is set by the sanitary permit and the approved-product list; no bedroom-to-tank value is published here.", "confidence": "Medium-High for formula; permit-specific application", "publication_status": "Publishable only with prominent permit/product warning", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": null, "highest_bedroom_at_or_below_1500": null }, { "state": "Wyoming", "verification_tier": "Compiled - primary source cited; re-verification in progress", "provenance_code": "A", "status": "A - Direct statewide schedule", "control_level": "Statewide minimum; delegated/local permit review may apply", "bed1": 1000, "bed2": 1000, "bed3": 1000, "bed4": 1000, "bed5": 1150, "bed6": 1300, "increment_or_formula": "150 gal per bedroom over 4", "design_flow_gpd_per_bedroom": null, "rule_citation": "Wyoming Water Quality Rules, Chapter 25, septic-tank sizing provision", "source_url": "https://wyoleg.gov/ARules/2012/Rules/ARR16-018.pdf", "source_type": "Official final rule filing", "effective_or_current_date": "Filed 2016; currentness rechecked 2026-07-20", "derivation": "Copied directly from official provision", "override_flags": "Local/delegated permit requirements and engineered systems", "notes": "The official rule package states 1,000 gallons through 4 bedrooms and adds 150 gallons per bedroom above 4. This corrects the common but unsupported +250-gallon assumption.", "confidence": "Medium-High", "publication_status": "Publishable with source-date disclosure", "last_checked": "2026-07-20", "highest_bedroom_at_or_below_1000": 4, "highest_bedroom_at_or_below_1500": 6 } ] }