Well Water and Septic by Region: Who Is Off the Public Pipe in 2023
The short answer
10.4 percent of occupied US homes, 13,863,000, draw their water from an individual well and 18.5 percent, 24,616,000, are on a septic tank or cesspool, according to the 2023 American Housing Survey. New England leads on wells at 20.0 percent; the East South Central states lead on septic at 36.8 percent. Outside metro areas, 46.0 percent of homes are on septic.
What the table shows
A home that is off the public water main or the public sewer carries its own infrastructure: a pump, pressure tank and treatment for a well; a tank and drain field for septic. Both are plumbing work that municipal customers never pay for. The American Housing Survey records each home’s main water source and its sewage system, which gives a direct count of how much of the country is outside the public pipe and where.
| Census division | Individual well | ± | Septic or cesspool | ± |
|---|---|---|---|---|
| New England | 20.0% | 2.2 | 30.1% | 1.6 |
| Middle Atlantic | 13.7% | 1.2 | 17.3% | 1.1 |
| East North Central | 15.9% | 1.5 | 18.0% | 1.3 |
| West North Central | 11.9% | 3.2 | 16.9% | 2.9 |
| South Atlantic | 11.9% | 1.8 | 22.1% | 1.8 |
| East South Central | 4.4% | 1.5 | 36.8% | 3.1 |
| West South Central | 4.9% | 0.8 | 15.8% | 1.4 |
| Mountain | 7.4% | 1.3 | 12.4% | 1.6 |
| Pacific | 4.8% | 1.0 | 9.8% | 1.1 |
| United States | 10.4% | 0.6 | 18.5% | 0.6 |
Source: calculated by The Plumbing Brief from the AHS 2023 National PUF; national totals match the Census Bureau’s published estimates (13,863,000 wells; 24,616,000 septic). Margins are 90 percent, in percentage points.
Sourced figures
- Homes whose primary water source is an individual well: 13,863,000 (±738,000). Source: AHS 2023.
- Homes on a public or private system serving six or more units: 119,015,000 (±861,000). Source: AHS 2023.
- Homes on a septic tank or cesspool: 24,616,000 (±766,000). Source: AHS 2023.
- Of those, standard tank and subsurface leach field: 23,294,000; pump-distributed systems: 784,000; elevated, treated-effluent or other: 538,000. Source: AHS 2023.
- Homes on public sewer: 107,884,000 (±875,000). Source: AHS 2023.
- Homes on both a well and septic: 12,152,000 (±681,000). Source: calculated from the AHS 2023 PUF.
- Share of well homes also on septic: 87.7 percent. Share of septic homes also on a well: 49.4 percent. Source: calculated from the AHS 2023 PUF.
- Well share outside metro areas: 26.6 percent; inside metro areas: 7.7 percent. Source: calculated from the AHS 2023 PUF.
- Septic share of mobile homes: 48.1 percent; of detached houses: 24.1 percent. Source: calculated from the AHS 2023 PUF.
- Septic share of homes built 2010 or later: 14.7 percent; built 1980 to 1999: 22.9 percent. Source: calculated from the AHS 2023 PUF.
- Owner-occupied homes on septic: 24.8 percent; renter homes: 6.6 percent. Source: calculated from the AHS 2023 PUF.
By type and age of home
| Group | Individual well | ± | Septic or cesspool | ± |
|---|---|---|---|---|
| In a metro area | 7.7% | 0.4 | 13.9% | 0.5 |
| Outside metro areas | 26.6% | 2.6 | 46.0% | 2.3 |
| Single-family detached | 13.6% | 0.7 | 24.1% | 0.7 |
| Single-family attached | 1.4% | 0.4 | 2.7% | 0.7 |
| 2 to 4 units | 2.0% | 0.6 | 3.0% | 0.7 |
| 5 to 49 units | 0.3% | 0.1 | 0.6% | 0.2 |
| 50 or more units | 0.1% | 0.1 | 0.4% | 0.2 |
| Mobile home | 27.0% | 2.7 | 48.1% | 2.7 |
| Before 1940 | 9.9% | 0.9 | 14.3% | 1.0 |
| 1940 to 1959 | 7.7% | 0.8 | 13.0% | 0.9 |
| 1960 to 1979 | 10.9% | 0.8 | 19.5% | 1.0 |
| 1980 to 1999 | 12.3% | 0.9 | 22.9% | 0.9 |
| 2000 to 2009 | 11.5% | 1.0 | 20.8% | 1.1 |
| 2010 or later | 7.4% | 0.9 | 14.7% | 1.0 |
| Owners | 13.9% | 0.7 | 24.8% | 0.8 |
| Renters | 3.8% | 0.4 | 6.6% | 0.4 |
What we calculated
Nine in ten well homes are also on septic
Formula. Homes with both an individual well and a septic system, divided by all homes with an individual well.
Calculation. 12,152,000 / 13,863,000 = 87.7 percent (±1.0).
Finding. Wells and septic come as a pair. A home off the water main is almost always off the sewer too, so the 12,152,000 homes on both carry the full private water and wastewater system. The reverse is weaker: only 49 percent of septic homes are on a well, because many suburban homes take public water but were never sewered.
Limitations. Both figures are national. The combination rate varies by region and cannot be estimated precisely below division level.
New construction is moving onto public systems
Formula. Well and septic shares by year built.
Calculation. Septic rises from 13.0 percent for homes built 1940 to 1959 to 22.9 percent for 1980 to 1999, then falls to 14.7 percent for homes built since 2010. Wells follow the same arc, peaking at 12.3 percent and falling to 7.4 percent.
Finding. The exurban building boom of the 1980s and 1990s put more homes on private systems than any other period. Homes built since 2010 are back toward the older-stock rates, consistent with more building inside serviced areas.
Limitations. Some older homes have been connected to public systems since construction, so the year-built pattern describes today’s systems, not the systems each home was built with.
Outside metro areas, nearly half of homes are on septic
Formula. Septic share of homes outside any metropolitan area.
Calculation. 46.0 percent (±2.3) against 13.9 percent inside metro areas.
Finding. Rural plumbing is a different trade. Septic pumping, drain field repair, well pumps and pressure tanks are routine work outside the metros and rare inside them.
Limitations. Metro status uses 2013 OMB delineations as coded on the PUF. Exurban counties that have since been added to metros are classified on the older basis.
If you quote one number
- 13.9 million US homes, 10.4 percent, are on a private well.
- 24.6 million US homes, 18.5 percent, are on septic.
- One in five New England homes is on a well.
- 37 percent of homes in Kentucky, Tennessee, Alabama and Mississippi are on septic.
- Outside metro areas, 46 percent of homes are on septic and 27 percent are on wells.
Download the data
Every share in this report with its margin of error. Published under a Creative Commons Attribution 4.0 licence. Attribution: The Plumbing Brief.
Well water and septic shares by division, metro status, building type, age and tenure (AHS 2023) (CSV)
How this report was built
Methodology
Source. 2023 American Housing Survey National Public Use File, version 1.1, downloaded from the Census Bureau on 4 October 2026. The AHS is sponsored by HUD and conducted by the Census Bureau; the 2023 national sample covers about 133.2 million occupied homes once weighted.
Universe. All occupied housing units.
Items used. WATSOURCE (1 public or private system serving 6 or more units, 2 individual well serving 5 or fewer, 3 other), SEWTYPE (septic codes 02 to 06 grouped), with DIVISION, OMB13CBSA, BLD, YRBUILT and TENURE as breakdowns. Breakdowns by tenure and year built also connect to households lacking complete plumbing altogether, covered in homes without complete plumbing.
Estimation. Every estimate is a weighted total using the PUF final weight (WEIGHT). Before any cross-tabulation was run, the national totals were reproduced against the Census Bureau’s own published Table Creator figures; every national figure quoted in this report matches the published estimate exactly.
Margins of error. Calculated from the 160 replicate weights supplied on the PUF (REPWEIGHT1 to REPWEIGHT160) by successive difference replication, variance = 4/160 × Σ(replicate − full)², at the 90 percent confidence level (1.645 standard errors). The method reproduces the Census Bureau’s published margins exactly for the national rows checked (for example 11,215,000 homes with an inside leak, ±346,000). Percentages carry margins in percentage points.
Derived figures. All cross-tabulations by year built, building type, tenure, division and metro status, all rates and all ratios are calculated by The Plumbing Brief from the PUF. They are not published Census tables.
Retrieval date. 4 October 2026.
Data limitations
- Everything here is self-reported by the household. A leak the occupants did not notice, or forgot, is not counted, so true incidence is likely higher than measured.
- The AHS 2023 is a single cross-section. It shows how rates differ between kinds of homes, not how any home changes as it ages.
- Year built, building type and tenure overlap heavily: older homes are more often rented and more often in multi-unit buildings. The breakdowns here are one variable at a time and do not separate those effects.
- Census divisions are the finest national geography the PUF supports. State and metro rates cannot be produced reliably from this file.
- Small groups carry wide margins. Where two margins overlap, the difference between the groups should not be treated as established.
- A well serving six or more homes counts as a public or private system, not an individual well. Small community wells are therefore in the public group.
- The AHS does not report water quality testing or well depth. The US Geological Survey and state health departments hold that data.
Source quality ranking
Tier 1. US Census Bureau and US Department of Housing and Urban Development, American Housing Survey 2023, National Public Use File v1.1, household file; AHS 2023 Table Specifications and PUF Estimates for User Verification; AHS 2023 Definitions (Appendix A); AHS 2023 Value Labels Package.
Tier 2. None used. Tier 3. None used.
Excluded. Insurance-industry claim frequencies and leak-sensor vendor statistics. Both describe customers of a product, not a representative sample of US homes, and neither publishes a sampling method.
Summary for reporters
About 13.9 million occupied US homes, 10.4 percent, draw their water from an individual well and about 24.6 million, 18.5 percent, are served by a septic tank or cesspool, according to the 2023 American Housing Survey. An analysis of the survey’s public use file by The Plumbing Brief found the highest well share in New England, at 20.0 percent, and the highest septic share in the East South Central division, at 36.8 percent. Outside metropolitan areas 46.0 percent of homes are on septic. Nearly nine in ten well homes, 87.7 percent, are also on septic, meaning about 12.2 million households run both their own water supply and their own wastewater system.
Angles this supports
- One in five New England homes runs on its own well
- Off the grid by plumbing: 12 million homes have both a well and septic
- Nearly half of rural homes are on septic
- The 1990s exurb boom put a record share of homes on septic
- Where septic is the norm: Kentucky, Tennessee, Alabama and Mississippi
Questions this answers
How many US homes use well water? About 13.9 million occupied homes, 10.4 percent, had an individual well as their primary water source in 2023 (AHS).
How many US homes are on septic? About 24.6 million, 18.5 percent. Almost all use a standard tank and leach field.
Which region has the most well water? New England, at 20.0 percent of homes, followed by the East North Central division at 15.9 percent.
Which region has the most septic systems? The East South Central division (Kentucky, Tennessee, Alabama, Mississippi), at 36.8 percent, then New England at 30.1 percent.
Do homes with wells also have septic? Usually. 87.7 percent of well homes are also on septic.
Are new homes built with septic? Less often than in the 1980s and 1990s. 14.7 percent of homes built since 2010 are on septic, against 22.9 percent of homes built 1980 to 1999.
What share of mobile homes are on septic? 48.1 percent, and 27.0 percent are on a well.
Can I get state-level figures? Not reliably from the national AHS file. Census division is the finest geography it supports.
How to cite this report
The Plumbing Brief, “Well Water and Septic by Region: Who Is Off the Public Pipe in 2023”, https://theplumbingbrief.com/well-water-and-septic-by-region/, accessed [date].
Last reviewed: 2026-10-04.
