Aerobic Treatment Unit (ATU) Cost and Maintenance Contract

Short answer: published cost guides put an aerobic treatment unit (ATU) at roughly $10,000 to $20,000 installed, well above a conventional system's $3,000 to $8,000. In Texas, an ATU also carries its own maintenance rule: for the first two years it runs under an initial service policy, and after that a single-family owner can either maintain the system personally or get a new contract, commonly priced around $300 to $500 a year. That self-maintenance choice doesn't exist for commercial, speculative residential, or multifamily property, where TCEQ requires a contract.

What an ATU costs to install

An aerobic treatment unit injects oxygen into the treatment tank to speed up bacterial breakdown of waste, which is why it gets used on sites a conventional gravity system can't handle. See our septic system types compared guide for how an ATU differs from a conventional, chamber, mound or drip system.

Published cost guides put a conventional gravity-fed system at roughly $3,000 to $8,000 installed, versus $10,000 to $20,000 or more for an ATU, because of the added mechanical components, electrical connections and engineering the design needs. A Central Texas-focused source gives the same $10,000 to $20,000 range for a residential ATU, and another published guide puts ATU installation at $5,000 to $15,000 or more, so expect real quotes to vary by site difficulty inside that broad band.

These are published ranges, not a quote. See our septic system installation cost guide for what else moves the final number, and our enquiry form to get a real number for your property.

Texas's maintenance-contract rule for ATUs

Under Texas Commission on Environmental Quality (TCEQ) rules (30 TAC Chapter 285), a new OSSF, including an ATU, starts under an initial two-year service policy that runs "for two years from the date the OSSF is first used." For a new single-family home that date is the builder's date of sale; for an existing home it's the date the permitting authority issues its notice of approval.

At the end of those two years, the rule gives a single-family owner a choice: "the owner of an OSSF for a single family residence shall either maintain the system personally or obtain a new maintenance contract." That self-maintenance option is not available to every owner, though. The same rule states: "An owner may not maintain an OSSF under the provisions of this section for commercial, speculative residential, or multifamily property." For those owners, a contract is the only option under this rule.

This contract requirement traces back to how TCEQ classifies an ATU. Separately, 30 TAC 285.32(c)(3) states that "ongoing maintenance contracts are required for all proprietary treatment systems except those systems maintained by homeowners under the provisions of §285.7(d)(4)" and an ATU is a proprietary treatment system under this chapter, which is why it carries this contract-or-self-maintain structure at all. A conventional gravity-fed system isn't a proprietary treatment system, so this particular contract rule doesn't reach it.

If you do pay for maintenance rather than self-maintaining, the work has to be done by someone TCEQ has approved: "in order to perform maintenance on an OSSF, an individual must either be licensed by the TCEQ as a maintenance provider or registered by the TCEQ as a maintenance technician and employed by a licensed maintenance provider." Check a provider's license before signing; see our guide to hiring a septic company for how to confirm that.

This section describes Texas's rule specifically, the one we verified against TCEQ's own published rule text. Other states set their own requirements for ATUs and other mechanical systems; don't assume Texas's contract-or-self-maintain structure applies where you live.

What the maintenance contract costs

Published Texas pricing puts an ATU maintenance contract commonly around $300 to $500 a year, described as covering three inspections, TCEQ reporting, and basic maintenance. A separate cost breakdown puts aerobic maintenance-contract pricing at $175 to $600 a year depending on the service level, consistent with the Texas figure sitting in the middle of that range. These published figures describe what's typical, not every contract's specific terms, so get the exact scope in writing from whoever you hire.

ATU vs. conventional: the costs side by side

Situation	Conventional system	Aerobic treatment unit (ATU)
Installed cost	Roughly $3,000 to $8,000, published guides say	Roughly $10,000 to $20,000, published guides say
TCEQ ongoing maintenance-contract requirement (Texas)	Not a proprietary treatment system under this rule, so this contract requirement doesn't apply	Single-family: self-maintain or contract, after the first 2 years. Commercial/speculative residential/multifamily: contract required
Typical contract cost where one applies (Texas)	n/a under this rule	Commonly $300 to $500 a year

For how often a conventional system itself needs pumping and inspection, see our septic system maintenance schedule; for component lifespan and replacement cost on either system type, see how long a septic system lasts.

Which one fits your situation

If your lot's soil and size can support a conventional system, it's usually both the cheaper install and the system this particular TCEQ contract rule doesn't reach. If your soil, water table, lot size or local rules require an ATU instead, budget for the higher install cost plus an ongoing decision: self-maintain if the property is a single-family residence and you're willing to do the work, or carry the roughly $300-to-$500-a-year contract if you'd rather not, or if the property is commercial, speculative residential, or multifamily, where that contract isn't optional. A site evaluation is what actually determines which system your property qualifies for. Our septic company directory can connect you with a company that does that evaluation in your area, or use our enquiry form for a quote that covers both scenarios.

Frequently asked questions

Does Texas require an ATU maintenance contract?

For the first two years after a new ATU is put in use, yes, under the initial service policy. After that, a single-family owner may either maintain the system personally or get a new contract. Owners of commercial, speculative residential, or multifamily property are not allowed to self-maintain and must carry a contract.

Can I maintain my own ATU instead of paying for a contract?

Yes, if the property is a single-family residence and the initial two-year service policy has ended. TCEQ's rule allows that owner to maintain the system personally instead of signing a new contract. That option does not exist for commercial, speculative residential, or multifamily property, where a contract is required.

What does a Texas ATU maintenance contract typically include?

Published Texas pricing describes a typical contract as covering three inspections a year, TCEQ reporting, and basic maintenance, commonly priced around $300 to $500 a year. Published guides describe what's typical, not every contract's specific terms, so confirm the exact scope with the provider.

Sources

Checked October 2026. Source URLs confirmed live at build time. Costs shift with inflation and local labor/material prices; treat these as planning ranges, not a quote.

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