Ontario · Part 8 · Updated July 2026
Septic permits in Ontario: who issues them, what to submit, what it costs
Every new, replaced, altered or repaired septic system in Ontario needs a permit before a shovel touches the ground. Here is the whole thing in plain English — from the first phone call to the final inspection.
The short version: a permit is required, it is issued locally, the application is mostly math and drawings, and the fee is the cheap part. The expensive part is the design paperwork — unless you do it yourself.
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1 Something’s wrong2 What it costs3 The permit4 Who designs it5 The paperwork6 Approval
Quick answer
You need a septic permit in Ontario for: a new system, a full replacement, a tank replacement, a bed repair, an alteration — and often for additions and renovations that add bedrooms, add fixtures, or grow the floor area by 15% or more. Permits are issued locally by your municipal building department, a public health unit, or a conservation authority. The application is reviewed under Part 8 of the Ontario Building Code.
What triggers a septic permit
The obvious ones: building a new home on septic, replacing a failed system, replacing just the tank, repairing a leaching bed. The ones that surprise people: finishing a basement with a new bathroom, adding a bedroom, adding a second suite, or converting a seasonal cottage to year-round use. The Building Code re-tests your system on paper whenever the load grows — more bedrooms, more fixtures, or 15% more floor area — and if the old system cannot carry the new load, the addition permit waits until the septic question is answered.
Do not start early
Building or repairing a sewage system without a permit is an offence under the Building Code Act. Worse in practice: the inspector can make you dig it up. Nothing gets backfilled until it passes inspection — uncovering a finished bed is the most expensive way to learn this rule.
Who issues septic permits
It depends where you live. Three kinds of offices handle Part 8 in Ontario: most municipalities run it through their own building department (all of Simcoe County and Muskoka work this way), some districts delegate to the public health unit (Algoma Public Health, for example), and a few watersheds use a conservation authority (the North Bay-Mattawa Conservation Authority, or the Ottawa Septic System Office run by the Rideau Valley Conservation Authority). Not sure which one is yours? Use the free authority finder — pick your municipality and it tells you who reviews septic where you live.
What goes in the application
Township packages vary in layout but ask for the same things, because it all comes from the same law:
- The provincial Application for a Permit to Construct or Demolish, plus Schedule 1 (designer) and Schedule 2 (installer)
- Design calculations: total daily design flow (Q), septic tank sizing, and leaching bed sizing from your soil’s percolation time (T-time)
- A site plan to scale, in metric, with a north arrow: property lines, buildings, wells (yours and the neighbour’s), the proposed system, and every clearance distance
- A cross-section drawing showing grades, materials, and the depth to water table and bedrock
- Soil evidence: test hole logs and T-time results — many offices want the T-time from a licensed testing agency
- The application fee
Want to see what a complete package looks like before you start? Here is a full 26-page sample — township forms filled in, drawings, worksheets, and every number explained.
What a septic permit costs
The permit fee itself is the small line: typically $350 to $750 for a new or replacement system depending on the municipality (some publish lower fees for tank-only replacements or bed repairs — The Blue Mountains, for example, lists $625 for a new or replacement system, $100 for a tank replacement, and $200 for a bed repair). The big line is the design paperwork: septic designers typically charge $800 to $2,000 to produce the calculations, site plan and cross-section. That is the part Ontario law lets you do yourself on your own property — more on that below.
The timeline: five steps
1. Completeness review. The office checks the application against its checklist. Incomplete applications get returned — the single most common delay.
2. Site inspection. Most authorities visit before issuing. Have the test pit open at the bed location and your lot lines clearly staked.
3. Permit issued. Now you can dig — and only now.
4. Pre-backfill inspection. The inspector checks the open excavation: trenches, stone, pipe, tank, separation to soil and water table. Do not cover anything until it passes.
5. Final grading. Mound topsoil to shed rain, seed it, keep vehicles off the bed forever.
The part nobody tells you
The township does not design your system and does not want to. They review what you submit. Someone has to produce the calculations and drawings — and in Ontario, on your own residential property, that someone is allowed to be you. That single rule is worth $800 to $2,000.
Design it yourself — legally
Ontario homeowners can design and build their own septic system on their own land. The exemption is written into the Building Code (Div. C, 3.2.5.1). What the township still requires is a complete, correct application. Start with the owner-builder guide, and when you are ready to produce the paperwork, run the free 2-minute septic check to see where your project stands.
Costs beyond the permit
Budget the whole picture before you commit: what a new septic system costs in Ontario if you are building, or replacement costs if you are dealing with a failed system. And if you are not sure the system is actually dead, read pumping vs replacement first.
Septic permit questions, answered
Do I need a permit to replace just the septic tank?
Yes. A tank replacement is an alteration to a sewage system and needs a permit in most municipalities. It is usually the cheapest permit class.
Can I start digging before the permit is issued?
No. Construction may begin only after issuance, and nothing may be backfilled before the pre-backfill inspection passes.
How long does a septic permit take in Ontario?
With a complete application: commonly two to four weeks including the site visit, varying by office and season. Incomplete applications are returned and restart the clock.
Does my building permit depend on septic approval?
On unserviced lots, yes — municipalities generally will not issue the house permit until the septic system is approved or verified. Sort septic early so the house does not stall.
Who can design the septic system?
A qualified designer (BCIN), an engineer, a licensed installer who designs — or you, the homeowner, for your own system on your own property.
Ready to sort the paperwork?
Answer the questions, check every distance, and print a permit-ready package — the same math the townships review.
Go deeper on permits
The complete permit package →Every form, worksheet and drawing the township wants, on one list.Septic before the building permit →How the gate works on new builds — and how to pass it in a week.New home? Septic comes first →The build sequence that keeps septic off your critical path.Failed an inspection? →What actually happens next — timelines, options, real costs.