In this article
Anyone who lived through the August 2014 storm in Metro Detroit remembers what happened to basements across Warren, Roseville and the rest of south Macomb County. When that much rain falls that fast, the public sewers fill, and the water takes the easiest way out. For many homes, that was the basement floor drain. A backwater valve is the device designed to stop it.
What a backwater valve does
A backwater valve is a one-way gate installed on the main sewer line where it leaves the house. Water and waste flow out toward the street as usual. If the flow reverses, a flap closes and blocks the sewer from pushing back into the home.
Why sewers back up in heavy rain
In older parts of Metro Detroit, storm water and sewage share the same pipes. In a severe storm the system can fill completely. When the level in the street sewer rises above your basement floor drain, the sewage flows toward your house instead of away from it. Nothing is wrong with your own plumbing when this happens. The blockage is the city system itself.
Signs your home is at risk
- The basement has backed up during heavy rain before
- Neighbors on your street have had storm backups
- You have a finished basement, or a basement bathroom or laundry
- The house sits low compared with the street
Backwater valve or sump pump?
They solve different problems. A sump pump removes groundwater that collects around and under the foundation. A backwater valve stops sewage from coming back up the drain line. A house can need one, the other or both, and one does not replace the other.
What it will not do
- It does not stop water seeping through foundation walls or the floor
- It does not help if the blockage is in your own sewer line between the house and the valve
- While the flap is closed, your own drains have nowhere to go, so using water in the house during a storm can fill the basement from the inside
That last point matters. During a storm heavy enough to close the valve, hold off on laundry, showers and the dishwasher until it passes.
Maintenance
A backwater valve has a moving part that sits in a sewer line, so it needs a look once a year. Most have an access cover in the basement floor. The flap should move freely and the seal should be clean. A valve jammed open by debris protects nothing.
Installation
Installing a backwater valve means opening the basement floor or digging outside to reach the main line, cutting the valve in and restoring the floor. It is a job for a licensed plumber, and most communities require a permit. Some cities have offered help with the cost in the past, so it is worth asking your city hall before you start.
Common questions
Does a backwater valve stop all sewer backups?
It stops backups that come from the public sewer. It does not stop a backup caused by roots, grease or a broken pipe in your own line.
Do I still need sewer backup insurance?
Yes. A valve lowers the risk. It does not remove it, and standard homeowners policies often exclude sewer backup unless an endorsement was added.
How do I know if I already have one?
Look for a round or rectangular access cover in the basement floor near the front wall, separate from the floor drain. If you are not sure, we can check.
We work on sewer lines across Macomb County and give you a flat-rate price before the work. See our sewer repair service and sump pump service, or call (586) 943-4158.
