Almost every region of the country is continuing to see a decline in the presence of private water and sewer systems in new homes, according to a new survey conducted by the National Association of Home Builders.
The states of Arizona, Colorado, and New Mexico are bunched together by the NAHB study in a regional reading showing that only 9% of new homes last year featured individual septic systems, a decline from 10% the previous year.
The figures were equally low in the Pacific region, which is made up of California, Oregon, Washington, Hawaii, and Alaska, where the overall figure is 7%, compared with 8% in 2023.
Lowest of all is the West South-Central region comprising Texas and Louisiana, seeing septic tank systems in 5% of new homes, compared to 6% in 2023.
States with the greatest number of new homes with individual septic tank systems were seen in New England, which saw an increase in such options from 38% of homes in 2023 to a large 49% last year.
The states of the Midwest, which include Michigan, Ohio, Indiana, Illinois, and Wisconsin – all in what the NAHB calls the East North Central region – saw an increase in septic tank construction from 23% in 2023 to 28% in 2024.
“Nationally, the majority of new homes were connected to public water systems,” noted an NAHB narrative accompanying the survey results. The same holds true for sewage systems, with 84% of new single-family homes in 2024 connected to a public sewer system.
Overall, notes the NAHB, “the share of new homes built with individual septic tanks has been generally on a decline across most regions since 2010.”
According to a recent U.S. Census Bureau study, around 25% of all existing American homes have septic tanks, from a high of 55% in Vermont to a low of around 10% in California.
July 25, 2025
By Garry Boulard
Photo courtesy of Environmental Protection Agency
