If your property has an advanced treatment unit, Ontario requires you to keep an ongoing maintenance agreement with a qualified service provider for as long as the unit is in use. It isn’t optional, it isn’t a manufacturer’s upsell, and it typically runs $300 to $600 a year.
Most owners inherit one of these systems when they buy a waterfront or constrained-soil property, discover the contract requirement at closing or afterwards, and have no idea what they’re actually paying for.
Here’s what the agreement covers, what it costs, and what happens if it lapses. For the wider picture on how these systems work, start with our guide to advanced treatment units in Ontario.
The Quick Answer
| Detail | |
|---|---|
| Who needs one | Owners of Class 4 systems using a treatment unit, and tertiary systems |
| Why | Ontario Regulation 332/12 ties the unit’s approval to ongoing servicing |
| Typical annual cost | $300-$600, depending on the unit and visit frequency |
| Typical visit frequency | Once or twice a year, some units require more |
| What it covers | Inspection, adjustment, sampling on some units, a report |
| What it does not cover | Pumping the tank, parts, repairs, emergency calls |
| Still need pumping? | Yes. $300-$600 for a standard tank, on the usual 3-5 year interval |
| If it lapses | System is out of compliance; issues at resale, reinspection, and insurance |
The most common misunderstanding: the service contract is not a pumping contract. They’re separate, and you need both.
Why This System Type Carries an Obligation Others Don’t
A conventional septic system is passive. Gravity moves water, bacteria do the work, and nothing needs electricity or adjustment. If nobody touches it for four years, it keeps functioning as designed.
An advanced treatment unit is active. It uses aeration, media, or both to produce a much higher-quality effluent, and it depends on mechanical components staying in tune. Our aerobic vs anaerobic comparison covers the difference in treatment terms.
The regulatory logic follows from that. These units are approved on the basis of a performance standard, and they only meet it if they’re serviced. So Ontario ties the approval to ongoing maintenance rather than trusting that a mechanical system will look after itself for twenty years.
That’s also why these units get approved on sites where a conventional bed wouldn’t be permitted: small waterfront lots, shallow soil over bedrock, high water tables, and sensitive shorelines. Our waterfront septic rules guide covers where these constraints bite hardest around the Kawartha lakes.
What a Service Visit Actually Includes
Contracts vary by manufacturer and provider, but a standard visit generally covers:
- Inspecting and testing the aerator, blower or pump, depending on the unit type
- Checking and cleaning filters, screens and diffusers
- Verifying the control panel and confirming that the alarm actually works
- Checking effluent clarity and, on some units, taking a sample
- Measuring sludge and scum accumulation to advise on pumping timing
- A written service report, which is the document that proves compliance
That last item is the one to hold onto. When you sell, when a reinspection program comes through, or when an insurer asks, the service reports are the evidence. Keep them filed with your permit and design drawings.
What the contract typically excludes: pumping the tank, replacement parts, repairs beyond adjustment, and after-hours emergency response. Those are billed separately, so read the agreement rather than assuming.
What It Costs to Run One of These, All In
Setting expectations properly, because these systems cost more to own than a conventional bed and that’s the trade for being allowed to build on a difficult site.
Service agreement: $300 to $600 a year.
Pumping: still required. Treatment units have a settling compartment that accumulates solids like any tank. A standard pump-out runs $300 to $600, generally on a 3 to 5 year interval, though some units want it more often. This surprises owners regularly.
Electricity: an aerator running continuously is a real line item on a rural power bill.
Parts: aerators, blowers and pumps are wear items. Pumps in septic service last 7 to 10 years and replacements run $600 to $1,500. Filters and diffusers are cheaper and more frequent.
The unit itself: these have a finite service life, and eventual replacement is more expensive than a conventional tank.
Across a decade, a treatment unit costs meaningfully more than a conventional system. That’s not an argument against it. On a lot where a conventional bed can’t be permitted, the alternative isn’t a cheaper system, it’s no system.
What Happens If You Let It Lapse
Nothing dramatic on day one. The consequences accumulate.
The system drifts out of spec. An unserviced aerator that fails silently means the unit is discharging poorly treated effluent while looking normal from the surface. On a shoreline lot, that’s exactly the outcome the higher standard existed to prevent.
You’re out of compliance. The approval was conditional on maintenance. Without it, the system doesn’t meet the terms it was permitted under.
Reinspection programs will find it. Mandatory reinspection programs check documentation, and a treatment unit with no service history is an immediate flag. Our guide on septic reinspection programs covers how these run.
Resale gets complicated. A buyer’s inspector will ask for service records. Missing records on a treatment unit mean the buyer prices in a full assessment and possibly a replacement, and they’re right to.
Insurance claims get harder. Where a policy covers septic-related damage, an insurer looking at a lapsed mandatory maintenance requirement has a straightforward argument for declining.
The alarm stops being a warning. These units alarm on failure, which is a real safety feature. An alarm you’ve been ignoring for months because nobody explained it isn’t protecting you.
A property owner near Fenelon Falls bought a lakefront place in 2023 with a tertiary unit installed in 2016. The contract had lapsed when the previous owner’s provider stopped serving the area, and nobody had picked it up. By the time it was reinstated in 2025, the blower had failed at some unknown point, and the media needed replacing. The catch-up bill was just over $3,000. Two years of contract would have been about $900.
If You’ve Just Bought One of These
Do these five things in the first month:
- Identify the unit. Manufacturer and model, off the control panel or the tank lid. You cannot arrange servicing for a unit nobody has identified.
- Get the permit and design file from the City of Kawartha Lakes. It tells you what was approved and under what conditions.
- Find out whether a contract is active, and with whom. Ask the seller’s lawyer if you’re still in the transaction.
- Arrange servicing with a provider qualified for that unit. Not every septic contractor services every manufacturer’s equipment.
- Start a file for service reports, and keep it with the permit. It’s the document set that protects you at resale.
The Ontario Association of Onsite Wastewater Professionals is a reasonable starting point for understanding what qualified servicing looks like.
Frequently Asked Questions
Is a maintenance contract legally required for an advanced treatment unit in Ontario?
Yes. Under Ontario Regulation 332/12, systems that rely on a treatment unit are approved on the condition that an ongoing maintenance agreement with a qualified service provider is maintained for as long as the system is in use. It’s a condition of the approval, not a manufacturer’s recommendation, and letting it lapse puts the system out of compliance.
How much does an advanced treatment unit service contract cost per year?
Typically $300 to $600 a year, depending on the unit type and how many visits it requires. Most contracts cover one or two scheduled visits with inspection, adjustment, and a written report. Pumping, parts and repairs are usually billed separately, so read what’s included rather than assuming the annual fee covers everything.
Do I still need to pump the tank if I have a treatment unit?
Yes. Treatment units have a settling compartment that accumulates sludge and scum like any septic tank, and it has to be pumped out. Most run on the standard 3 to 5 year interval, though some manufacturers specify more frequent service. A standard pump-out costs $300 to $600, and it’s separate from the annual service agreement.
What happens if the service contract on my treatment unit lapsed years ago?
Reinstate it and expect a catch-up assessment. An unserviced unit may have failed components that nobody noticed, because these systems can look normal from the surface while treating poorly. The immediate risks are non-compliance at reinspection, complications at resale when a buyer asks for service records, and a weaker position on any insurance claim.
Can any septic company service my treatment unit?
Not necessarily. Servicing generally requires familiarity with the specific manufacturer’s equipment, and some manufacturers restrict servicing to trained providers. Start by identifying the unit’s make and model from the control panel or tank lid, then confirm that a prospective provider actually services that equipment before signing anything.
Not Sure What’s Installed on Your Property?
If you’ve inherited a system nobody explained, the first step is identifying what you actually have and what it needs. That’s a straightforward site visit.
Call (705) 702-5526 or book an assessment. Serving the whole City of Kawartha Lakes with no travel surcharge and no minimum distance.