This is general information, not legal advice. Regulations change and counties differ, so check with your local health department or a licensed operator about your own system.
What Counts as an AOSS
In Virginia, an alternative onsite sewage system (AOSS) is any septic system that isn’t a plain tank and gravity drainfield. If your system has a treatment unit, a pump, a control panel, an alarm, a drip field or a mound, it’s almost certainly an AOSS. These systems do more than a conventional tank, so the state expects them to be looked after by a professional.
The regulations are in Chapter 613 of Title 12 of the Virginia Administrative Code, usually written 12VAC5-613. They’re run by the Virginia Department of Health (VDH) and the local health departments. The three things they require of a home-sized system are an operator, lab samples, and reports.
Operator Visits: At Least Once a Year
Every AOSS owner must have the system “operated and maintained by an operator” (12VAC5-613-140). That means a Licensed Operator, licensed by the Virginia Board for Waterworks and Wastewater Works Operators and Onsite Sewage System Professionals, not just a pumper.
How often the operator has to come depends on how much wastewater the system is designed to handle (12VAC5-613-150, Table 4):
| Design flow | First visit | After that |
|---|---|---|
| 1,000 gallons a day or less (almost every home) | Within 180 days of the operation permit | Every 12 months |
| 1,001 to 10,000 gallons a day | First week of operation | Every 3 months |
| 10,001 to 40,000 gallons a day | First week of operation | Every month |
A yearly visit is the floor, not the ceiling. The system’s O&M manual (the manufacturer’s instructions the owner must keep at the property) can call for more, and many treatment units do. At each visit the operator checks the tank, the treatment unit, pumps, floats, alarms and the drainfield, does the routine maintenance, and writes it all down.
Lab Samples: Every Five Years for Most Homes
The operator takes a sample of the treated water (the effluent) at the end of treatment, before it goes to the soil, and sends it to a lab. The lab checks BOD5 (a measure of how much organic matter is left) and, when the system has to disinfect, fecal coliform or chlorine residual (12VAC5-613-100).
- First sample: within 180 days of start-up, for every small AOSS.
- Generally approved treatment units: after that, one grab sample every five years.
- Units that aren’t generally approved: four more samples in the first two years, then once a year. The owner can ask to drop to every five years once five samples in a row pass.
- Systems that discharge straight to ground water: every quarter, and never treated as generally approved.
A system with a soil treatment area sized for plain septic tank effluent doesn’t need lab sampling at all. Sample results go to the local health department by the 15th of the month after the sample was taken.
Reports: Filed in MyHD by the 15th
After every visit the operator files a report with VDH “using a web-based system” and pays the filing fee (12VAC5-613-190). Today that system is VDH’s MyHD portal. The deadline is the 15th of the month after the visit. Fairfax County asks for the same deadline for the inspection reports it receives.
The report has to include at least:
- the operator’s name and license number, and the date and time of the visit;
- why the operator was there (routine visit, repair, sampling);
- a plain summary: the system is working as designed, it should be fine after routine maintenance, or the owner needs to act;
- every adjustment, repair and replaced part;
- field measurements, sample results and the lab’s name;
- a certification of when the owner got a copy.
The owner’s side (12VAC5-613-140) is simpler but easy to forget: keep an operator at all times, follow the O&M manual, keep the manual and the operator’s log at the house, show them to the health department on request, and pass them to the next owner when the house sells. If the home is in a Chesapeake Bay Preservation Area, the county’s pump-out ordinance applies too. See how often to pump a septic tank in Virginia.
How TankVault Keeps Track of This
TankVault puts each system’s inspection, sampling and report due dates on one list for the operator, on the schedule above for its type, and sends the homeowner a reminder before a visit is due. After a visit, the report stays on the office’s list with its MyHD due date until it’s filed; the operator downloads a ready-to-file copy, enters it in MyHD, and taps Mark Filed. Homeowners get a free app that shows what their system needs and when. See what it does for septic companies and for homeowners.
A system that discharges to a stream instead of a drainfield follows a stricter schedule; see discharging systems and the VAG40 permit. Working across the state line? Compare North Carolina operator inspections.
Questions and Answers
How often does an AOSS have to be inspected in Virginia?
For a home-sized system (1,000 gallons a day or less), a licensed operator must visit at least once every 12 months, with the first visit within 180 days of the operation permit (12VAC5-613-150, Table 4). Larger systems get quarterly or monthly visits.
How often is a lab sample required?
An initial sample within 180 days of start-up, then once every five years for a generally approved treatment unit. Units that aren’t generally approved are sampled more often at first, then yearly (12VAC5-613-100).
When is the operator’s report due?
By the 15th of the month after the visit, filed through VDH’s web-based system (12VAC5-613-190). The report must say whether the system is working as designed and certify when the owner got a copy.
What does the homeowner have to do?
Keep an operator, follow the O&M manual, keep the manual and the operator’s log at the property, and pass them on to the next owner (12VAC5-613-140).
Sources
- 12VAC5-613-100: Performance requirements and sampling
- 12VAC5-613-140: Owner responsibilities
- 12VAC5-613-150: Operator visit frequency (Table 4)
- 12VAC5-613-190: Reports
- VDH: Alternative Onsite Sewage System O&M reporting
- Fairfax County Health Department: Sewage and Water
Last reviewed October 18, 2026. This is general information, not legal advice. Regulations change and counties differ, so check with your local health department or a licensed operator about your own system.