Guide
Aerobic septic system: how it works and Texas rules
An aerobic treatment unit (ATU) pumps air into the wastewater so oxygen-using bacteria can break it down further than a conventional tank does. The treated, disinfected effluent is usually spread by surface (spray) irrigation or drip lines. That is why ATUs are common on small lots, shallow soil, and the rocky Hill Country ground found in much of Central Texas.
How common are they here?
In 2024, authorized agents in the eight counties covered here permitted more than 6,113 new or replacement septic systems. 3,471 of them used surface (spray) irrigation, which in Texas requires secondary treatment such as an ATU (TCEQ OARS 2024 data).
Typical parts
- Trash/pretreatment tank
- Aeration chamber with an air pump (aerator or compressor)
- Clarifier
- Chlorinator (tablet feeder) or other disinfection
- Pump tank and spray heads or drip field
- Control panel with audible and visual alarm
The maintenance rule
Under 30 TAC §285.7, the installer must provide an initial two-year service policy. After that, a single-family owner must either sign a new maintenance contract or maintain the system personally. See maintenance contracts and doing it yourself.
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FAQ
Do aerobic systems need a maintenance contract in Texas?
The installer must provide an initial two-year service policy. After that, the owner of a single-family home may sign a new contract or maintain the system personally (30 TAC §285.7(d)(4)). Commercial and multifamily systems need a contract.
How often is an aerobic system inspected?
A licensed maintenance provider inspects and reports at least once every four months, or every six months if the system has qualifying electronic monitoring (TCEQ).