London, ON onsite wastewater guide

Septic systems in London: permits, records, inspections and property checks

Begin with service status, not maintenance history. A pump receipt can exist without answering what system is installed, whether it was approved or what it serves. A septic question near London is a property-file question first. Municipal sewer may serve one part of the area while another parcel relies on onsite wastewater.

First questionSewer or onsite?
Local lensSouthwestern Ontario
Before buyingRecords + condition
Before workLocation + capacity

First, confirm this property’s wastewater service

A city-area guide cannot tell whether a specific parcel is connected to sewer or has an onsite system.

Local septic / permit route

Use the local authority route below for septic approvals, permits or records. Confirm sewer connection separately with the municipality or utility.

Open local septic / permit page →

Onsite system confirmed

Find the parcel’s system approvals and verify current rules with the responsible local authority before work.

Start with provincial guidance →

Service unknown

Check utility bills and permit records; ask the local authority to confirm current service before planning an onsite inspection or repair.

How to confirm service →
Provincial rule: In Ontario, most onsite sewage systems with design capacity at or below 10,000 litres per day are regulated under the Building Code Act. Permits are typically issued by the local municipality or, in some areas, a health unit; larger systems may require provincial environmental approval. Open provincial / regional onsite-wastewater authority →

London separates private sewage from sewer service

London’s permit guide lists installation, replacement or repair of a private sewage system. The same page also lists sewer-system installation, repair and replacement, which is a distinct service question. If a buyer is looking at a fringe property, start with utility records and the approved sewage file; a listing’s “septic” description should be checked against the actual service connection and plans.

London’s Building By-law also contains sewage-permit application provisions, but the details depend on the project and current forms. For an addition or new dwelling use, give the designer both the building proposal and the existing onsite approval so capacity can be reviewed before plans are fixed. Use the City’s current permit guide and ask Building Services to identify the proper submission for this address. A blocked private drain connected to the municipal main calls for a different diagnostic and permit route than a failed septic treatment field; commissioning the wrong kind of work wastes time.

Who approves septic work around London?

Ontario regulates most residential onsite sewage systems under Part 8 of the Building Code. Systems with a daily design flow of 10,000 litres or less are generally administered by a municipality, health unit or conservation authority; larger systems fall under the environmental approval regime.

Confirm the exact Part 8 authority before applying. New systems, replacements, major repairs, additions or changes that increase design flow can require permit review, site/soil information, design calculations and inspections before covering.

Local approval route: London separately lists private sewage installation, replacement and repair and municipal sewer-system work in its permit guidance.

Official sources for this guide

If sewage is backing up or surfacing, stop using affected fixtures and contact a qualified professional or the responsible authority. Never enter a septic tank.

Authority check for this area

Last verified: September 28, 2026. Local and provincial/regional source routes checked. Confirm the parcel’s service status, responsible authority and current requirements before work. How we research these guides →