What is the minimum lot size for a home with a septic system in Texas?
TexasReviewed October 2026
For newer subdivisions, Texas septic rules set a floor. Under 30 Texas Administrative Code Section 285.4, single-family subdivision lots that use individual on-site sewage facilities (septic systems) must be at least one-half acre if served by a public water supply, and at least one acre if not served by a public water supply, such as when the lot relies on a private well. Older subdivisions created before January 1, 1988 may still use septic on smaller lots if other rules are met. Counties and cities can set larger minimum lot sizes, and soil and setback requirements can push the practical size higher. Ask the local septic permitting authority before buying.
Check your local rule. This varies by state, county or city. Your permitting office has the final word; the official lookup pages below show you who that is.