On-Site Sewage Facilities

On-Site Sewage Facilities (OSSF) are wastewater systems designed to treat and dispose of effluent on the same property that produces the wastewater. A septic tank and drainfield combination is the oldest and most common type of OSSF, although newer aerobic treatment units exist which represent scaled down versions of municipal sewage treatment plants. OSSFs account for approximately 25 percent of all domestic wastewater treatment in the United States. Tarrant County regulates the OSSF Inspection and Permit process for 23 cities and the unincorporated parts of the county.

Learn more about our Environmental Health Contract Cities

On November 11, 2025, the Tarrant County Commissioner's Court adopted, under Court Order 146317, that all subdivisions of single-family dwellings shall have lots of at least one acre, net of drainage and floodplain easements.

In order to assure that wastewater is disposed safely, a permitting and inspection program requires that all OSSFs must be in substantial compliance with state regulations.

Click here for a copy of the OSSF Rules and Regulations. 

If you are needing to report a violation, please fill out the OSSF Investigation Request. For any other questions, comments, or concerns regarding OSSFs, please contact Ekpen Okoruwa at 817-212-7082.

It is very important to realize that nearly all of the unincorporated land in Tarrant County falls within the Extra Territorial Jurisdiction (ETJ) of existing cities. An ETJ is an area outside of a city’s limits where the city is allowed to require subdivision of acreage to meet minimum city requirements.

Learn more about Extra Territorial Jurisdictions

There are several state requirements that must be met to properly subdivide acreage in the unincorporated areas of Tarrant County. State law requires that conditions be evaluated as to the suitability of the site if OSSFs are to be used.

Learn more about Subdividing Land

The Environmental Division staff has prepared a list of short answers for the most common OSSF inquires. The FAQ webpage may help you with questions about the installation and maintenance of your OSSF.