What backwater valve installation involves
The valve goes in the main building drain inside the house, downstream of every fixture, usually near the front wall. Installing one in an existing home means cutting the basement floor, exposing the drain line, cutting in the valve and setting it in an access box with a removable lid. The floor is then patched around the box.
The flap normally hangs open so water flows freely to the street. If sewage starts to flow back, it lifts and seals. The valve must be accessible so it can be cleaned and checked.
While a backwater valve is off, water from your own fixtures cannot exit the home either. During a storm warning, go easy on laundry and showers.
Older houses versus newer builds
Older homes are where valves matter most. Many were built before backwater valves were required, often with floor drains sitting lower than the street sewer. In heavy rain, combined or overloaded sewers can push water back into those basements. Homes in older parts of the city often have a single main drain, which makes placement straightforward.
Newer homes may already have a valve installed. It is worth finding it, checking it is accessible and that the lid is not buried under flooring. Some newer layouts have more than one sewer outlet, which complicates matters.
Questions to ask on the phone
- Has the basement ever taken sewage, and during what weather?
- Where is the main cleanout, and is the floor finished there?
- Do you have weeping tile connected to the sanitary sewer?
- Is a permit needed? In most cases, yes.
Durham municipalities have offered basement flooding protection subsidies at various times. Check the City of Oshawa's current program details before you book, as rules and amounts change.
Aftercare
Lift the access lid twice a year and look at the flap. Remove any debris and make sure it moves freely. Never store anything on the access box. Our winterizing outdoor taps note is a good companion fall chore. If the house also has worn fixtures, ask about faucet repair and backflow prevention, which protects the drinking water side.