An ATU is the one septic system that genuinely will not run unattended. It has a blower, diffusers and a control panel, and the approval it was installed under almost always carries a servicing condition.
The blower is what makes an ATU an ATU. When it stops, or when the diffusers blind and stop delivering air into the chamber, the biology that does the treating dies back within days and what leaves the unit is no cleaner than ordinary tank effluent.
The system keeps working in the sense that water keeps moving, which is exactly the problem: nothing backs up and nobody notices, while a dispersal area sized for treated effluent starts receiving untreated effluent. On a site chosen for an ATU specifically because a conventional bed would not fit, that is serious.
So the visit checks air delivery rather than just power, verifies the alarm by triggering it, and looks at the disinfection stage where one is fitted. Component failures go to pump and float replacement, and the tank ahead of the unit still needs pumping.
Blower checked
How it works
What a service visit covers
Panel and history
Run hours, fault log and alarm history read first, because the panel usually shows what has been happening between visits.
Air delivery
Blower output and diffuser condition checked, since a running blower and actual aeration are not the same thing.
Process and disinfection
Mixed liquor appearance and settling checked, plus chlorine or UV where the permit requires a disinfection stage.
Alarm and records
High-level alarm triggered and reset, then the visit recorded in the form the approval condition expects.
Why the records matter here more
Somebody may ask to see them
Conventional systems are largely unregulated once they pass final inspection. Treatment units usually are not: the approval commonly requires a maintenance contract in force and a service record available on request, and that obligation follows the property rather than the owner.
In practice this matters most at sale. A buyer's inspection on a property with an ATU will ask for the service history, and an absent one is a real problem at closing rather than a paperwork nuisance.
Keeping it is not difficult provided the visits are routed rather than remembered, which is what a service contract exists for. The same applies to the certification a lender may want.
Contract in forceUsually required
At saleAsked for
The propertyFollows
Maintenance services
Other maintenance work
The routine items that keep a system out of trouble.
Set by the manufacturer and the approval, commonly a few visits a year. Unlike a conventional tank, this is usually a condition rather than a recommendation.
Treatment stops within days while water keeps flowing, so nothing backs up and nothing looks wrong. That silence is exactly why the alarm and the scheduled visit matter.
Yes. Solids still settle and still have to be removed. The unit treats effluent; it does not eliminate sludge. See pumping schedule.
Some checks are simple, but where the approval requires a contract with a qualified servicer, doing it yourself does not satisfy the condition however well you do it.
Continuous electricity for the blower plus scheduled servicing. Those running costs belong in the decision when an ATU is being chosen. See septic system cost.
Start a service history from today and have the unit assessed properly on the first visit. Missing history cannot be reconstructed, but a documented restart is far better than nothing at sale.
