What aerobic treatment unit means
An aerobic treatment unit is a septic system that pumps air into the wastewater so oxygen loving bacteria break it down more fully before it is released.
Also called ATU, aerobic septic.
Where it matters on a septic job
ATUs have pumps, blowers and alarms, so they need regular service, often under a required maintenance contract. That contract is recurring revenue for a septic shop.
The numbers, with sources
- EPA says systems with electrical float switches, pumps or mechanical parts should be inspected more often, generally once a year. (EPA)
What it costs
The septic system installation cost guide has the typical job at $7,200 and the usual range at $3,800 to $11,000. The guide shows its sources and what moves the price. The septic system cost calculator prices a job line by line.
Work it out
- Free calculator: Septic system cost calculator
- Cost guide: Septic system installation cost
- Free template: Service agreement template
- Licensing: Septic installer license rules by state
- Tools, templates and guides: Free septic resources
Sources: EPA, How to care for your septic system. Checked October 9, 2026.