Ontario · Owner-builder · 2026
The owner-builder septic permit package: exactly what the township wants to see
You are allowed to design and build your own septic system in Ontario. The catch is the paperwork: the application only moves if every form, worksheet, drawing and soil record is there. Here is the complete list — and what the examiner checks on each piece.
The short version: a complete package is the provincial application, Schedule 1 and 2, the design worksheets (flow, fixtures, tank, bed), a scaled site plan, a cross-section, soil and T-time evidence from your test holes, and the fee. Miss one piece and the application comes back.
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Homeowner’s Guide44 pp.
Costs, permits, contractor vetting, and the owner-builder path — updated for the 2026 Building Code.
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1 Something’s wrong2 What it costs3 The permit4 Who designs it5 The paperwork6 Approval
The part nobody tells you
Designers charge $800–$2,000 just for the paperwork in these quotes.
Ontario law lets you do that part yourself, on your own property. OntarioSepticDesigner.ca turns your answers into the same 26-page package the township clerk sees every day — calculations, drawings, forms, all of it.
What a complete package contains
Every Ontario approval authority — township building department, health unit, or conservation authority — works from the same law, Part 8 of the Building Code. The paperwork below is what they all need before anyone reviews your design. File it complete and you are the easiest application on the desk that week.
✓Application for a Permit to Construct or Demolish — the provincial form, sections A through I
✓Schedule 1 — Designer information, with the homeowner exemption box checked
✓Schedule 2 — Installer information (you, as owner-builder on your own property)
✓Design worksheets — daily design flow, fixture units, tank sizing, leaching bed calculation
✓Site plan to scale, metric, north arrow, every setback distance shown
✓Cross-section drawing with grades, materials, water table and bedrock depth
✓Soil evidence — test hole logs and T-time results, licensed agency where required
✓Application fee per the authority’s current schedule ($350–$750 typical)
The worksheets: four calculations the examiner re-checks
Daily design flow (Q). Bedrooms set the number: 3 bedrooms is 1,600 L/day, 4 is 2,000, 5 is 2,500. The Code then adds flow for the largest of: bedrooms over five, floor area over 200 m², or fixture units over 20. Get Q wrong and every number downstream is wrong.
Fixture units. A count of every drain in the house — toilets are 4, most sinks and tubs 1.5. Over 20 units adds daily flow.
Tank sizing. Twice the daily flow, never under 3,600 L, two compartments, effluent filter on the outlet. For most 3-bedroom homes the 3,600 L minimum governs.
Leaching bed. One line of math the examiner knows by heart: L = Q × T ÷ 200. Your soil’s percolation time drives total pipe length; no run over 30 m; trenches 1.6 m on centre. A T of 18 on a 3-bedroom house means 144 m of pipe in 5 runs.
The four things examiners bounce most
Missing neighbour’s well on the site plan. No reserve bed area shown. Site plan not to scale (or no north arrow). T-time from nobody — some offices only accept results from a licensed testing agency. Every one of these turns a two-week review into a two-month bounce cycle.
The site plan: what must be on it
✓Property lines, lot dimensions, and the legal description
✓House, driveway, decks, pools, outbuildings — existing and proposed
✓Wells: yours AND the neighbours’, with distances
✓Lakes, streams, ponds and ditches with setback distances
✓The proposed tank and bed, with every clearance dimension
✓The reserve bed area — empty ground saved for a future replacement bed
✓Slopes and drainage direction, plus any flood-prone areas
✓North arrow and scale bar — metric, max 11×17 paper in most offices
The cross-section: prove the vertical numbers
The drawing that shows what the inspector cannot see from above: trench depth and width, the stone layer (150 mm below the pipe, 50 mm above), original and finished grade, and the one number that kills more designs than any other — 0.9 m of separation between the bottom of the bed and the high water table or bedrock. Your test pit proves where the water sits; the drawing proves your bed stays above it.
The $18,950 line that never appears on a quote
A real worked example: 3-bedroom bungalow, conventional bed. Tank supplied and set, pipe, stone, fabric, one day of machine and labour, permit allowance — $13,049 with HST. The same job quoted at $32,000. The gap is design fees, markup, and labour you may not need to buy.
Two minutes on the free checker shows the numbers your own lot generates — daily flow, tank size, risk level — before anyone quotes you.
Three ways to get this package done
| Route | What it costs | What you get |
|---|---|---|
| Hire a designer | $800–$2,000 | Full package done for you; you wait on their schedule and revisions |
| Do it from scratch | Your evenings | Free, but every worksheet, drawing and clearance table is yours to research and get right |
| Ontario Septic Designer | $99.99 | Answer questions, check every setback, print the complete package the same day — township forms filled in, drawings included |
Whichever route you pick, the reviewing authority holds it to the same standard. Look at a complete 26-page sample package to see the finish line before you start.
Package questions, answered straight
Do I need an engineer to stamp my septic design?
Not for a typical residential Class 4 system you design for your own property — the homeowner exemption covers you. Engineers come in for commercial systems, over 10,000 L/day, or where the authority specifically requires one for a difficult site.
How many copies does the township want?
Most offices now take digital PDF submissions; some still want two paper sets. Check your authority’s current checklist before filing — it is the first question to ask on the phone.
Can I submit before my perc test is done?
No point — the bed calculation needs the T-time, and the examiner cannot review a design without it. Test first, design second, file third.
What happens after I file?
Completeness review, a site inspection with your test pit open, then the permit. Build only after issuance, and never backfill before the pre-backfill inspection passes.
What does the permit itself cost?
Typically $350–$750 for a new or replacement system depending on the municipality — the cheap line on the project. The paperwork above is where the real money goes if you hire it out.
Print the package the clerk recognizes
Answer the questions. Check every setback. Print the whole package — township forms filled in, site plan and cross-section included. $99.99 instead of $800–$2,000.