Texas septic setback distances: wells, water and property lines

Under Texas rules, a septic tank must be at least 50 feet from a private water well and 5 feet from a property line, and a drain field at least 100 feet from a private well and 75 feet from a creek or pond. Your local permitting authority can require more. [1] [2] [5]

Last checked Oct 18, 2026 · sources below · about this page

Not legal advice. These are state minimums. Confirm the distances for your lot with your local permitting authority before you build, buy or dig.

Where the distances come from

Table X of the state septic rules: The state septic rules (Texas Administrative Code, Title 30, Chapter 285) set minimum separation distances in Table X, "Minimum Required Separation Distances for On-Site Sewage Facilities", in section 285.91. The table was last amended effective Jul 6, 2023. All distances are in feet. [1] [2] [3]
OSSF: Texas rules call a septic system an on-site sewage facility, or OSSF: an on-site sewage disposal system. [4]
Who enforces the distances: Your permitting authority. That is usually an authorized agent: a local government, such as a county, that TCEQ has given the power to enforce the state septic rules. Where there is no authorized agent, the TCEQ regional office is the permitting authority. [4] [5]
Local rules can be stricter: TCEQ says local permitting programs can be more stringent than the state minimums, so your county may require larger distances than the ones on this page. [5]

Distances from wells and water

Distances run from the part of the system named in each column.

State minimum distances from water, in feet (Table X); your local permitting authority can require more
From	Septic tank	Drain field (soil absorption system)	Spray area edge (surface application)	Drip lines (drip irrigation)
Private water well or underground cistern	50	100	100	100
Public water well	50	150	150	150
Private water line	10	10	No distance set	10
Public water supply line	10	10	10	10
Stream, pond, lake, river or creek (from normal pool level)	50	75 (50 for a low-pressure dosed field with secondary treatment and disinfection)	50	25 to 75, depending on the soil's application rate (50 with secondary treatment and disinfection)

Sources: [1] Texas Administrative Code, via the Texas Secretary of State; [2] Texas Administrative Code, via Cornell Legal Information Institute; [9] Texas Administrative Code, via Cornell Legal Information Institute

Note: Table X has more rows and columns than shown here, and footnotes for some cells. Read the full table for your situation.

Drain field and surface water: A conventional drain field (the rule's soil absorption system) must be at least 75 feet from streams, ponds, lakes, rivers and creeks, measured from normal pool elevation. A septic tank and the edge of a spray area must each be at least 50 feet from them. Your local permitting authority can require more. [1] [2] [9]
Public wells and water lines: Table X notes that the public drinking water rules (30 TAC Chapter 290) may add to or change the distances from public wells and public water lines. [1]

Distances from buildings and property lines

Tanks and drain fields

A septic tank or drain field must be at least 5 feet from foundations, buildings, swimming pools, property lines and other structures. Your local permitting authority can require more. [1] [2] [9]

Spray areas (aerobic systems)

The edge of a spray area must be at least 20 feet from a property line and 25 feet from a swimming pool. Table X has no distance from buildings for spray areas. A footnote lets the property line distance drop to 10 feet when a timer controls the sprinklers. Some counties set larger distances: Travis County requires at least 25 feet from a property line, Comal County never allows less than 20 feet (so no timer reduction), and Williamson County's order keeps spray at least 20 feet from property lines and 10 feet from any part of a home. [1] [2] [10] [11] [12] [13]

Drip lines

Drip irrigation lines must be at least 5 feet from a property line and may not be placed under a foundation. Your local permitting authority can require more. [1] [2] [9]

Easements

Table X sets 1 foot from underground and overhead easements for most parts of the system, with no distance if the easement holder gives permission. Spray may reach the edge of an easement but not into it. Your local permitting authority can set a stricter rule. [1] [2] [9]

Permit-exempt systems on 10 acres or more

A single-family home on a tract of 10 acres or more can be exempt from a permit only if, among other conditions, every part of the system is at least 100 feet from the property line and the system meets the state standards. Some counties don't allow this exemption: Fort Bend County says it does not apply there, Kerr County requires a permit for new or upgraded systems regardless of tract size, and Comal and Travis counties require a permit regardless of acreage or lot size. Check with your local permitting authority. [5] [7] [8] [11] [10]

Counties that don't allow the 10-acre exemption

Some counties don't allow this exemption. Fort Bend County says the 10-acre exemption does not apply in the county. Since Aug 7, 2026, Kerr County has required a permit to install or upgrade any septic system, regardless of tract size. It says systems already in place that still meet the state exemption are not affected, unless the property has more than one home or, in the county's words, "a structure(s) serviced by an OSSF" (a septic system); the county's page doesn't explain that second exception further. Comal and Travis counties require a permit regardless of acreage or lot size. Ask your local permitting authority before relying on the exemption. [7] [8] [5] [11] [10]

About this page

The minimum distances Texas rules set between parts of a septic system and wells, water lines, creeks, buildings and property lines, from Table X of the state septic rules. It also explains who enforces them and why your county may require more.

Content last changed: Oct 18, 2026
Last verified: Oct 18, 2026
Sources: 13 sources, all primary, listed below
Not covered: Edwards Aquifer recharge zone rules; Every row of Table X (easements, slopes and lined beds are only summarized or left out); Your county's own distances

Contacts

Your local septic permitting authority
What they handle
Sets and checks the distances for your lot. Find it by county with TCEQ's OARS lookup.
Website
https://www.tceq.texas.gov/permitting/ossf/aa_search.html
Source
[6] Texas Commission on Environmental Quality (TCEQ)

Sources

Each fact above cites one or more of these by number. Accessed is the date the source was last re-read.

[1] Figure: 30 TAC §285.91(10), Table X. Minimum Required Separation Distances for On-Site Sewage Facilities. Texas Administrative Code, via the Texas Secretary of State. Primary source.
Supports: Every distance and footnote on this page: the official Table X figure in effect since Jul 6, 2023.
Publisher's date: Adopted 48 TexReg 3513 (Jun 30, 2023), effective Jul 6, 2023.
Accessed: Oct 18, 2026.
[2] 30 Tex. Admin. Code § 285.91, Tables. Texas Administrative Code, via Cornell Legal Information Institute. Primary source.
Supports: Section 285.91 includes Table X; last amended effective Jul 6, 2023.
Publisher's date: Notes: last amended effective Jul 6, 2023 (48 TexReg 3513).
Accessed: Oct 18, 2026.
[3] History Page, Chapter 285, On-Site Sewage Facilities. Texas Commission on Environmental Quality (TCEQ). Primary source.
Supports: No Chapter 285 amendment after the 2023 changes; 2024 quadrennial review.
Publisher's date: Latest entry: quadrennial review effective Mar 30, 2024.
Accessed: Oct 18, 2026.
[4] 30 Tex. Admin. Code § 285.2, Definitions. Texas Administrative Code, via Cornell Legal Information Institute. Primary source.
Supports: Definitions of OSSF, authorized agent and permitting authority.
Accessed: Oct 18, 2026.
[5] Getting a Permit for an OSSF - Such as a Septic System. Texas Commission on Environmental Quality (TCEQ). Primary source.
Supports: Local programs can be stricter; TCEQ regional office where no authorized agent; 10-acre exemption, including that it applies only where the local permitting authority does not require a permit.
Publisher's date: Page last modified Aug 10, 2026.
Accessed: Oct 18, 2026.
[6] OARS: Find a Local Contact (septic permitting authority by county). Texas Commission on Environmental Quality (TCEQ). Primary source.
Supports: Finding the local permitting authority.
Accessed: Oct 18, 2026.
[7] On-Site Sewage Facility Permits / Packets. Fort Bend County Environmental Health. Primary source.
Supports: The 10-acre exemption does not apply in Fort Bend County.
Accessed: Oct 18, 2026.
[8] Environmental Health Department On-Site Sewage Facility. Kerr County Environmental Health Department. Primary source.
Supports: Since Aug 7, 2026, a permit to install or upgrade any septic system regardless of tract size; existing systems that still meet the state exemption are unaffected unless the property has more than one home or, in the county's words, "a structure(s) serviced by an OSSF" (a septic system).
Publisher's date: Page describes the county OSSF order effective Aug 7, 2026.
Accessed: Oct 18, 2026.
[9] 30 Tex. Admin. Code § 285.10, Delegation to Authorized Agents. Texas Administrative Code, via Cornell Legal Information Institute. Primary source.
Supports: Local permitting authorities may adopt standards more stringent than the state rules.
Accessed: Oct 18, 2026.
[10] Travis County Code Chapter 448: Rules for On-Site Sewage Facilities. Travis County. Primary source.
Supports: Travis County: spray areas at least 25 feet from a property line; homeowners who maintain their own system must test and report like maintenance providers; no permit exemption by lot size.
Publisher's date: Document says amendments added through Nov 28, 2023.
Accessed: Oct 18, 2026.
[11] Comal County Rules for On-Site Sewage Facility. Comal County. Primary source.
Supports: Comal County: a permit for every system regardless of acreage; never less than 20 feet between a property line and the edge of a spray area.
Publisher's date: Scanned county order; TCEQ approval dated Nov 26, 2013.
Accessed: Oct 18, 2026.
[12] Order Adopting Rules of Williamson County, Texas for On-Site Sewage Facilities. Williamson County Commissioners Court. Primary source.
Supports: Williamson County order: spray at least 20 feet from property lines and 10 feet from a residence; homeowner maintenance needs training, a county contract form and testing and reporting results; pump tanks sized for a one-day reserve.
Publisher's date: Final revision in the county's Jan 12, 2021 Commissioners Court documents (unsigned); the same provisions appear in the 2017 order signed by the County Judge..
Accessed: Oct 18, 2026.
[13] Order Adopting Rules of Williamson County, Texas for On-Site Sewage Facilities (2017). Williamson County Commissioners Court. Primary source.
Supports: Williamson County 2017 order, signed by the County Judge: spray at least 20 feet from property lines and 10 feet from a residence; homeowner maintenance needs training, a county contract form and testing and reporting results; pump tanks sized for a one-day reserve.
Publisher's date: 2017 order in the county's Jul 11, 2017 Commissioners Court documents, signed by the County Judge; the day, month and clerk's attestation are blank.
Accessed: Oct 18, 2026.

Page history

Oct 18, 2026: Added at each state distance that local permitting authorities can require more, and named Travis, Comal and Williamson county spray-area rules that are stricter than the state's, and added Comal and Travis counties to the counties that don't allow the 10-acre exemption. Re-checked every source.
Oct 16, 2026: Added that some counties don't allow the 10-acre permit exemption, with Fort Bend and Kerr counties as examples. Re-checked every source.
Oct 13, 2026: First version of this page.