Before you start
- Wear gloves and eye protection
- Have a flashlight, a bucket and old towels ready
- Ask household members not to use water during the check
- Consult your valve's manual if you have it
Steps
- Remove the access cover over the valve in the basement floor.
- Look inside with a flashlight. The flap should be open, lying in the flow direction.
- Remove debris caught around the flap or seat.
- Check the seal for cracks or warping.
- Test movement by gently lifting the flap, if your model allows.
- Replace the cover securely.
During storms. When the valve closes during a sewer surcharge, your own drains cannot empty. Limit water use during heavy rain warnings.
Signs of trouble
- The flap is stuck shut or open
- Odours around the access cover
- Water around the valve after use
A valve that will not move or seal should be serviced or replaced; see backwater valve installation. Upgrading heating equipment at the same time? Read about tankless installation. Pressure concerns are covered in causes of low water pressure.
Worth knowing
Answers our Mississauga crew gives most
How often should I check it?
Each spring and autumn, plus after any severe storm.
Can the flap get stuck?
Yes, debris or grease can hold it open or shut.
Do all valves look the same?
No. Designs differ, so follow your model's instructions.