Adding a Suite on a Well and Septic: Trent Lakes and Havelock-Belmont-Methuen Rules
Updated · 8 min read · By Gilbert Brothers
In this guide
The short answer
For a suite on a well and septic system, the township's zoning by-law decides, and Trent Lakes and Havelock-Belmont-Methuen write very different rules. A Trent Lakes additional residential unit (ARU) is limited to one per lot, on at least 4,000 square metres, no larger than 85 square metres, with two parking spaces, one shared well and a Class 4 septic system. Havelock-Belmont-Methuen allows up to two additional units on a lot without municipal services if the sewage system has the capacity and a certificate of occupancy for potable (drinking) water is obtained. Both rule out lots near water and on private roads. Rules differ by property and change, so confirm with the township's building office before you start.
This page explains two townships' rules, and anyone planning a suite there can use it. Naming a township's office says who to ask, not where Gilbert Brothers works; the FAQ has the service area. Each rule comes from the township's own by-law or page as it stood on October 27, 2026.
The Municipality of Trent Lakes and the Township of Havelock-Belmont-Methuen each issue their own permits and take applications on Cloudpermit, an online permit system. Both took over septic permits from Peterborough Public Health in 2024 (Havelock-Belmont-Methuen on November 17).
The City of Peterborough's rules are in the Peterborough suite rules, the other Peterborough-area townships' are in the township suite rules, and Kawartha Lakes has its own: see the Kawartha Lakes registration steps.
The two by-laws side by side
| Trent Lakes (By-law B2025-070) | Havelock-Belmont-Methuen (section 4.35) | |
|---|---|---|
| Zones | Rural, Rural Residential, Hamlet Residential | Agricultural, Rural, Residential Type-1, Residential Type-2 |
| Units on a lot | One, in a detached dwelling or a detached accessory building | Up to two: one in the dwelling, one in an accessory building |
| Size | 85 square metres (915 square feet) at most, and no larger than the main unit | "Clearly subordinate" to the main unit. No figure |
| Minimum lot | 4,000 square metres | No figure in section 4.35 |
| Parking | Two spaces on the lot | One off-street space per unit, on top of the main unit's |
| Water and septic | One shared well. A lawful septic system, connected to a Class 4 | Proof the sewage system has capacity, and a certificate of occupancy for potable water |
| Road | Lot has direct access to a public road kept open year-round | Not on a lot reached by private roads, or where emergency services may be limited |
| Water | Not below a regulated floodline, or within 30 metres of the high water mark of a water body, watercourse or wetland | Not in an environmental protection zone or floodplain, or within 30 metres of a high water mark |
| Lakes | Not within 300 metres of an at-capacity or moderately sensitive lake trout lake. The by-law says 11 are included | Not within 300 metres of an "at-capacity lake" |
The Trent Lakes column comes from By-law B2025-070, passed September 2, 2025. The Havelock-Belmont-Methuen column comes from its zoning by-law consolidation, dated July 2025, which says it is prepared for convenience only.
Trent Lakes: what else the by-law says
A suite inside the house must also have a separate outside entrance, and every existing building on the lot must be lawful. The house and suite share one driveway. If the suite is added beside the house, the two must share a wall at least 5 metres long. A suite in a detached building must sit on one floor, within 15 metres of the house in the Rural Residential and Hamlet zones or 25 metres in the Rural zone.
The lot is ruled out if it has municipal water and a private septic system, or if a guest cabin or an accessory building with plumbing already stands on it. The 300 metre limit, measured from the high water mark, applies to at-capacity and moderately sensitive lake trout lakes. The by-law says the at-capacity lakes include Beaver, Fortescue, Cavendish, Concession, Pencil, Crystal, Bottle and Salmon, and the moderately sensitive lakes include Catchacoma, Gold and Mississauga. Because it says "include", the by-law does not say those 11 are the full list, so ask the building office whether a lake near your lot counts. The Municipality's September 2025 notice of passing describes these limits more broadly than the by-law text does: any lake trout lake, any lot on municipal water and any lot on a private road. Ask the building office which wording governs your lot.
An existing suite that was never approved may apply for a change of use permit under section 4.3.3. The Municipality is rewriting its zoning by-law in 2026, with the new one due in 2027, so this by-law may be replaced.
Havelock-Belmont-Methuen: what else the by-law says
The unit must be built for year-round living and meet the Ontario Building Code and Fire Code. It cannot go in a vacation or recreational dwelling, in a building that serves one, or in a dwelling that is accessory to a non-residential use. The consolidation uses "at-capacity lake" without naming the lakes, so ask the Township which ones it means. Section 4.35 also lets a legally existing garden suite be converted into a permanent unit, subject to the section's rules.
If your lot is in a settlement area with both municipal sewage and water, a different subsection applies. It allows up to two units inside the house when none is in an accessory building, or one inside and one in an accessory building, with one off-street space per unit.
The Township's building page and permit requirements sheet, as checked for this article, do not state these rules. The zoning by-law does, so quote section 4.35 when you call.
The permit path in each township
Trent Lakes. The ARU list on the building permits page asks for the application, a site plan, an energy efficiency summary, a conservation authority permit if applicable, an HVAC design, a sewage system permit, and drawings by a qualified BCIN designer (BCIN is the Building Code Identification Number). The page's FAQ also says owners may design for their own property. Ask which applies to a suite. The septic page says septic applications go in before or with the building permit, and the permit page says most home renovation permits are issued within 10 business days of a complete application. The office is at 705-738-3800.
Havelock-Belmont-Methuen. The sewage systems page lists what triggers a review of an existing system: more occupants, more bedrooms, new plumbing fixtures, construction over 15 per cent of the finished area, or a finished area over 200 square metres. The Township then issues a letter saying the system can carry the load, or asks you to resize or replace it. Inspections need 48 hours' notice, and the building office is at 705-778-2308. Rules differ by property and change; confirm with the township before you start.
What the fee schedules add up to
Trent Lakes' Schedule B is undated. A council report of October 6, 2026 lists the same $1.54 per square foot new-residential rate as the 2026 fee and proposes about 2.4 per cent more from January 1, 2027, with a public meeting on November 3, 2026. Havelock-Belmont-Methuen's By-law 2024-069 is headed "Building Permit Fees 2024".
| Line | Trent Lakes | Havelock-Belmont-Methuen |
|---|---|---|
| Finished basement | $0.83 per square foot, minimum $581 | Not listed separately |
| Renovation | $0.41 per square foot (minimum $287) for interior layout changes only. $0.83 (minimum $581) for "extensive" renovation: life safety system, HVAC or fire separation | $0.38 per square foot, listed as "Tenant Fit-up (Renovation)". Minimum permit $150 |
| Built without a permit | An added fee of 100% of the regular fee, up to $5,000 | Permit fee plus 100% |
| New Class 4 septic, up to 4,500 litres a day | $1,000 | $1,000 |
| Existing system inspection or review | $500 | $400 |
Here is a hypothetical, not a quote. Say a 900 square foot basement becomes a suite. At Trent Lakes' $0.83 that is $747, or $369 at the $0.41 line. At Havelock-Belmont-Methuen's $0.38 it is $342. Which line applies is for the building office to say. These figures leave out taxes, development charges if they apply, septic work, drawings and the cost of building, and they are the township's fees, not a price for any job.
North Kawartha and Marmora and Lake
The Township of North Kawartha's property development page says secondary units are permitted under its By-law 2019-016 and links an application to license a secondary dwelling unit. That form asks whether the unit is new or existing, where it sits, its size and its parking spaces. The by-law's PDF is a scan with no readable text, so this page states none of its rules.
The Municipality of Marmora and Lake's building page sends plans and inspections to the Building Inspection Services Board. It says permits are required to remove partitions, move plumbing fixtures, build a basement under an existing structure, build a secondary residence or change a building's use. Its building page states no ARU limits, and it invites you to ask the Building Department whether a finished basement or apartment is legal. The Municipality's zoning by-law was not checked, so this page states no ARU rule for it.
Before you spend on drawings
Confirm the township and the zone
Ask the building office for your zoning and whether an ARU is allowed on the lot.
Check the knock-outs
Private road, water setback, lake distance, existing cabin or plumbed outbuilding.
Ask about the septic system first
Both townships tie the unit to septic capacity.
Ask about fees and changes
A Trent Lakes report proposes a fee increase for 2027, and the Municipality is rewriting its zoning by-law.
If your home is inside the area Gilbert Brothers serves, which the FAQ explains, you can request a free estimate, and Gilbert Brothers replies within one business day. The rules above are the townships', and they apply whoever you hire. The finish-level rules for any basement are in the basement permit guide, and basement renovations has the rest.
Frequently asked questions
Can I add a suite in Trent Lakes if my lot is under 4,000 square metres?
Not under By-law B2025-070, which sets 4,000 square metres as the minimum lot area for a suite inside a dwelling or an accessory building.
Does Havelock-Belmont-Methuen name the lakes it excludes?
The consolidation says "at-capacity lake" without naming any. Ask the Township for the list.
Who issues the permit?
Each township's own building office, through Cloudpermit. Septic permits moved from Peterborough Public Health to both townships in 2024.
Do these rules apply in the City of Peterborough or Kawartha Lakes?
No. Both have their own. See the Peterborough rules and which office issues your permit.