Signs you need this
- Pump short-cycling or humming without moving water
- Water standing in the pit after rain
- Sewage pushing up through the floor drain
- Check valve slamming after every cycle
Kit on the van, and the method
- Pit liner, check valve and union fittings
- Float switch and alarm tester
- Wet vac and pump-out hose
- Backwater valve access-lid tools
Before we leave: Hose-fill the crock until the float lifts, then time a full start, empty and shut-off cycle.
How sewage gets in
During a severe storm, the sanitary sewer can receive more water than it was designed for, from leaky manholes, roof leaders still connected in older areas, and foundation drains tied in decades ago. When the street main fills, the water looks for the lowest openings it can find, and in many houses that is the basement floor drain.
What the valve does
A mainline backwater valve sits in the house drain under the basement slab, downstream of every fixture. Inside is a flap that stays open with normal flow. When water reverses from the street, the flap floats shut and seals. Most designs have a clear or removable lid giving you a view of the flap and a way to wipe it.
Installing one
- Camera the main to find its depth and route, and confirm it is in reasonable condition.
- Saw out a rectangle of floor above the drain.
- Excavate to the drain, cut out a length, and set the valve dead level with its arrow pointing streetward.
- Fit an access box to finished floor height so the lid can be reached.
- Backfill, compact, and pour new concrete around the box.
A permit from the Town of Whitby is normally required for this work, and an inspection follows. We arrange that and leave the excavation open until it is inspected.
Subsidy programs
The Town has run a flood-protection grant that put money toward the price of a backwater valve and associated work, with conditions such as permits and approved installations. Program details change, so check the Town's current terms before work begins. Our note on backwater valve care explains annual checks.
Its limits
This valve guards against sewer backup, not groundwater seepage through walls or a failed sump. Those are separate problems covered on sump pump installation and basement flooding repair.