Updated 18 April 2026
Read This Before Getting a Quote
Most US states require a mandatory $200-$400/year service contract on any aerobic treatment unit, for the life of the system. That is $4,000-$8,000 over a 20-year system lifespan on top of the installation cost. Most installer quotes do not include this ongoing obligation. Before accepting any ATU quote, ask: what is the annual service contract cost, who provides it, and is it legally required in my county?
An aerobic treatment unit (ATU) uses oxygen injection to treat wastewater to near-secondary standards - significantly cleaner than a conventional septic tank. This allows a much smaller drain field and makes ATUs permissible in locations where conventional and mound systems cannot be permitted. They are required or commonly used in failed-perc situations, high-water-table coastal sites, environmentally sensitive zones, and small lots in states like Texas and Florida where ATUs are a primary alternative to conventional systems.
Wastewater enters a pretreatment trash tank that separates large solids. Effluent then flows to the aeration chamber, where an electric aerator (air pump) continuously injects oxygen. The oxygen supports a dense population of aerobic bacteria that break down organic waste far more efficiently than the anaerobic bacteria in a conventional tank.
After aeration, the treated effluent flows to a clarifier chamber where residual suspended solids settle. Most state codes then require disinfection - either chlorine tablet feeders or UV disinfection - before the treated effluent is dispersed to a small drain field or, in some states, spray-irrigated on the surface. The treated effluent from a properly functioning ATU typically meets or exceeds secondary treatment standards.
| Line Item | Low | Typical | High |
|---|---|---|---|
| ATU unit (tank + aerator) | $4,000 | $7,000 | $10,000 |
| Engineered design (mandatory) | $1,500 | $2,500 | $3,500 |
| Permits and inspection fees | $500 | $1,000 | $1,500 |
| Electrical hookup | $500 | $900 | $1,500 |
| Small drain field installation | $1,500 | $2,500 | $4,000 |
| Installation and excavation labor | $3,000 | $5,000 | $8,000 |
| Disinfection system (chlorine/UV) | $300 | $600 | $1,000 |
| Total installed | $11,300 | $19,500 | $29,500 |
| Annual service contract (ongoing) | $200/yr | $300/yr | $400/yr |
| Electricity (aerator) | $150/yr | $225/yr | $300/yr |
| 20-year total cost of ownership | $19,800 | $33,500 | $51,500 |
20-year TCO includes install + 20 annual service contracts + 20 years electricity + 2 pump replacements (~$800 each). Does not include tank pump-outs ($300-$500 every 1-2 years).
The following states require a service contract on all ATU installations as a condition of permit approval. This is not optional in these jurisdictions - operating without a current contract is a health code violation:
Many other states require it by county rule rather than state law. Always confirm with your county health department before budget planning.
| Brand | Unit Cost |
|---|---|
| Norweco Singulair | $5,000-$8,000 |
| Hoot Aerobic | $4,000-$7,000 |
| Jet Inc. | $4,500-$8,000 |
| AquaSafe | $5,000-$9,000 |