Aerobic treatment unit service visits: what the contract actually covers

Why aerobic units come with a contract

A conventional septic system is passive: the tank settles solids, gravity carries effluent to the field, and nothing needs electricity. An aerobic treatment unit is a small treatment plant. EPA describes it as a system that injects oxygen into the treatment tank to boost the bacteria doing the work, notes that it needs electrical power, and says owners should expect regular maintenance for the life of the unit. EPA's general guidance is that systems with mechanical parts should be inspected about once a year and that a service contract matters precisely because of those parts.

What the rules actually require

Requirements depend on two things: whether your unit discharges off the lot, and which health district you live in.

If the unit discharges to a ditch or stream, it is covered by Ohio EPA's general permit for household systems, OHK000004, which took effect January 1, 2022 and expires December 31, 2026; a renewal, OHK000005, is in public notice. Ohio EPA's list of homeowner responsibilities under that permit includes:

• Keeping a local health district operation permit for the life of the system
• Operating under a maintenance contract with a service provider who is trained or certified by the manufacturer and registered with the local health department
• Annual diagnostic sampling, with the lab checking total suspended solids, ammonia, dissolved oxygen, and E. coli, plus chlorine on units that chlorinate
• Making sure the sample is collected and reported to the local health district, which the service provider or the district can handle
• Filing a coverage transfer form when the house is sold

Whether or not it discharges, the county sets the local cadence:

• Hamilton County Public Health inspects systems with mechanical components every year and requires a service contract for any mechanical system permitted on or after December 10, 2004. A registered service provider's documentation can replace the county inspection for a $32 operation permit.
• Clermont County Public Health assesses systems with electrical components every 19 months and discharging systems every 12, and every time-dosed system must carry a service contract with a registered service provider.
• Butler County General Health puts aerobic, mound, drip, and discharging systems on an annual operation permit and inspection.
• Warren County Health District issues discharging systems a three-year operating permit.
• Inside Cincinnati city limits, the Cincinnati Health Department licenses and inspects household systems every year.

Notice what is not on either list: a statewide quarterly visit. Some manufacturers and contracts schedule more frequent visits, so the cadence in your contract should follow the unit's product requirements and your county's rules.

What a service visit should cover

A thorough visit follows the flow through the unit:

• Aerator and controls. Confirm the aerator runs and delivers air, the timer settings are correct, and the alarm fires on test.
• Pumps and floats on units that dose effluent to a drip field or mound.
• Filters. Clean or replace air and effluent filters, and look for a flooded or bypassed filter, which Hamilton County lists among conditions requiring correction.
• Effluent appearance. Discolored, odorous, or turbid effluent points to a treatment problem.
• Disinfection, if the unit has it.
• Sludge level, so the pump-out is scheduled from a measurement.
• The soil side. Clermont County's Regulation 415 requires a service provider contracted for a unit that feeds a soil absorption component to service or monitor that component too.
• A written record of what was found, what was replaced, and when the next visit and sample are due.

How to compare two contracts

Put the quotes side by side and ask each company:

• Registration and training. Is the company registered with your health district as a service provider (Ohio requires registration for each category of work, renewed every calendar year), and is it trained or certified for your unit's brand? Hamilton County publishes service provider lists by company and by system type.
• Visits per year, and whether that cadence meets your county's permit and the manufacturer's requirements.
• The annual sample. For a discharging unit, is collection and reporting included?
• Paperwork. Will the company submit the proof of maintenance your district accepts?
• Alarm response. How fast does someone come out when the alarm sounds?
• Parts and pump-outs. Which parts are covered, and is pumping included or billed separately?

The cheapest contract is the wrong one if it leaves out the sample or the county paperwork, because those are what keep the operation permit current.

If you have no contract right now

Get one in place before the next county inspection, and ask for a first visit that checks everything, not just the routine list. For a discharging unit, confirm the annual sample is scheduled. If you are buying a home with an aerobic unit, ask the seller for the service history and the current operation permit, and plan to file Ohio EPA's transfer form after closing.

Our aerator maintenance FAQ covers the routine side of ownership, and if the alarm is already sounding, book a septic repair visit.