Septic System Ownership by State: 2026 Data Report
More than 21 million US households — roughly 1 in 5 American homes — rely on a private septic system instead of public sewer. But ownership rates vary dramatically by state, from over 55% in Vermont to under 10% in Nevada. This report compiles the most complete publicly available state-level data in one place.
Published: July 2026 · Sources: US EPA, US Census Bureau, NEIWPCC, state environmental agencies
21M+
US households on septic
1 in 5
Share of all US homes
55%
Vermont — highest in nation
46%
Southern share of all septic
Regional Breakdown
According to the EPA Septic Systems Fact Sheet, the South accounts for the largest share of US septic households, followed by the Midwest, Northeast, and West. In 35 states, more than a quarter of all households use septic systems. In nine states, the rate exceeds 40%.
| Region | Septic Households | Share of US Septic Total | Notes |
|---|---|---|---|
| South | 10.1 million | 46% | FL, NC, GA, TX lead in volume |
| Midwest | 4.8 million | 22% | MI, OH, WI, MN significant |
| Northeast | 4.2 million | 19% | VT, ME, NH highest % rates |
| West | 2.9 million | 13% | WA leads; CA/NV/AZ low % |
Source: EPA Septic Systems Fact Sheet (Census Bureau 2007 AHS data — most recent federal regional breakdown available). View source
State-by-State Septic Ownership Data
The table below compiles estimated septic ownership rates for all 50 states from EPA records, US Census housing surveys, NEIWPCC reports, and state environmental agency publications. Where exact state-level percentages are unavailable from federal sources, figures are derived from state agency reports and verified industry data.
Note: The US Census Bureau discontinued state-level septic data collection after 1990. Current estimates are compiled from the most recent available state agency reports and EPA housing surveys.
| State | Est. % on Septic | Est. Total Systems | Ownership Level |
|---|---|---|---|
| Vermont | ~55% | ~165,000 | High (30%+) |
| Maine | ~50% | ~330,000 | High (30%+) |
| New Hampshire | ~50% | ~300,000 | High (30%+) |
| Connecticut | ~25% | ~350,000 | Medium (15–30%) |
| Massachusetts | ~27% | ~600,000 | Medium (15–30%) |
| Rhode Island | ~20% | ~90,000 | Medium (15–30%) |
| North Carolina | ~48% | ~1,700,000 | High (30%+) |
| South Carolina | ~44% | ~900,000 | High (30%+) |
| Alabama | ~38% | ~800,000 | High (30%+) |
| Georgia | ~35% | ~1,500,000 | High (30%+) |
| Tennessee | ~33% | ~800,000 | High (30%+) |
| Virginia | ~33% | ~1,000,000 | High (30%+) |
| Mississippi | ~35% | ~450,000 | High (30%+) |
| Florida | ~30% | ~2,600,000 | High (30%+) |
| West Virginia | ~40% | ~350,000 | High (30%+) |
| Kentucky | ~35% | ~650,000 | High (30%+) |
| Arkansas | ~35% | ~500,000 | High (30%+) |
| Louisiana | ~25% | ~450,000 | Medium (15–30%) |
| Michigan | ~29% | ~1,300,000 | Medium (15–30%) |
| Ohio | ~24% | ~1,100,000 | Medium (15–30%) |
| Indiana | ~28% | ~750,000 | Medium (15–30%) |
| Minnesota | ~25% | ~600,000 | Medium (15–30%) |
| Wisconsin | ~30% | ~650,000 | Medium (15–30%) |
| Missouri | ~25% | ~600,000 | Medium (15–30%) |
| Iowa | ~22% | ~350,000 | Medium (15–30%) |
| Illinois | ~15% | ~700,000 | Low (<15%) |
| Kansas | ~20% | ~250,000 | Medium (15–30%) |
| Nebraska | ~18% | ~180,000 | Low (<15%) |
| South Dakota | ~25% | ~100,000 | Medium (15–30%) |
| North Dakota | ~20% | ~80,000 | Medium (15–30%) |
| Pennsylvania | ~26% | ~1,100,000 | Medium (15–30%) |
| New York | ~22% | ~1,300,000 | Medium (15–30%) |
| New Jersey | ~20% | ~600,000 | Medium (15–30%) |
| Maryland | ~22% | ~500,000 | Medium (15–30%) |
| Delaware | ~25% | ~110,000 | Medium (15–30%) |
| Texas | ~20% | ~2,000,000 | Medium (15–30%) |
| Oklahoma | ~30% | ~450,000 | Medium (15–30%) |
| Washington | ~33% | ~950,000 | High (30%+) |
| Oregon | ~25% | ~450,000 | Medium (15–30%) |
| Idaho | ~30% | ~220,000 | Medium (15–30%) |
| Montana | ~30% | ~160,000 | Medium (15–30%) |
| Wyoming | ~28% | ~75,000 | Medium (15–30%) |
| Colorado | ~15% | ~320,000 | Low (<15%) |
| Utah | ~15% | ~170,000 | Low (<15%) |
| New Mexico | ~20% | ~180,000 | Medium (15–30%) |
| Arizona | ~10% | ~280,000 | Low (<15%) |
| Nevada | ~8% | ~100,000 | Low (<15%) |
| California | ~10% | ~1,300,000 | Low (<15%) |
| Alaska | ~30% | ~100,000 | Medium (15–30%) |
| Hawaii | ~15% | ~90,000 | Low (<15%) |
Sources: US EPA ( epa.gov/septic), US Census Bureau Housing Surveys, NEIWPCC ( neiwpcc.org), Wind River Environmental, FindSeptic state directory.
Why Septic Ownership Varies by State
Five primary factors drive septic system prevalence across US states, as documented by the US EPA and the New England Interstate Water Pollution Control Commission:
1. Population Density
Densely populated urban states like California (~10%) have extensive municipal sewer infrastructure. Rural states like Vermont (~55%) and Maine (~50%) lack the population concentration to justify centralized systems across their entire geography.
2. Soil Composition
Septic drain fields require well-draining soil to filter and absorb treated effluent. Loamy New England soils and Southeast sandy soils are ideal. Dense clay soils in parts of the Midwest and West limit septic viability.
3. Housing Stock Age
Many Southern and rural Midwest homes were built before municipal sewer expansion reached those areas. Those homes were designed around septic from the start and were never connected to sewer infrastructure.
4. Geographic Topography
New England's dispersed rural landscape and mountainous terrain makes centralized sewer systems expensive and logistically difficult to build, making individual septic the practical default for most properties.
5. New Construction Trends
Approximately 16–25% of all new single-family homes built in the US still use septic systems, per the Census Bureau Survey of Construction (2023). In Oklahoma, 49% of all new homes built since 2002 used septic.
6. State Regulatory Environment
Some states like New Jersey enforce strict statewide septic standards. Others like Georgia delegate authority to county health departments, creating significant variation in installation costs and requirements within a single state.
Frequently Asked Questions
What state has the most septic systems?
Florida has the most septic systems by total count with over 2.6 million systems. Vermont has the highest percentage at approximately 55% of all households.
What percentage of US homes use septic systems?
Approximately 20% of all US households — about 21 million homes — rely on individual septic systems rather than public sewer, according to the US EPA.
Which region of the US has the most septic systems?
The South has the most septic systems, accounting for 46% of all US septic households. The Midwest follows with 22%, the Northeast with 19%, and the West with 13%, per EPA data.
Data Sources & Methodology
This report compiles data from the following primary sources. All figures are estimates based on the most recent available data. The US Census Bureau discontinued state-level septic data collection after 1990; current state estimates are derived from state environmental agency reports, EPA regional data, and verified industry publications.
- US EPA — About Septic Systems: epa.gov/septic/about-septic-systems
- EPA Septic Systems Fact Sheet (Census 2007 AHS): nepis.epa.gov
- US Census Bureau — Historical Housing: Sewage Disposal: census.gov
- NEIWPCC — Are Septic Systems Up to Speed?: neiwpcc.org
- EPA Report to Congress — Decentralized Wastewater (2022): epa.gov
- Minnesota Pollution Control Agency: pca.state.mn.us
- Washington State Dept of Ecology (2024): ecology.wa.gov
- OSU Extension — Septic System Trends in Oklahoma: extension.okstate.edu
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