Tom,

I currently finishing my basement and have heard/read that if the flood rim level of any fixtures is below the next upstream sewer manhole cover that a backwater valve should be installed to prevent sewage backup into the finished basement in the event there was a main sewer line block or other similar malfunction.

With my basement, all the waste pipe runs under my concrete floor out to the main (no pump needed), but my basement floor is lower in elevation than the next upstream sewer manhole cover.

Will a backwater valve help to prevent sewage back up into my basement? I haven't had any sewage backup problems before and the subdivision is only about 10 years old. Also my house sits up higher than any other house between the 2 sewer manholes so I assume one of my neighbors would have the problem before me if it was a main line problem.

The link below is one example I have found.

http://www.backwater-valves.com/Backwater-Valve-Diagram.asp

Did ypu have a floor drain in the basement before you remodeled?

Unless your house main is lower then the street main out in front about the only way that you can get a back up in your basement is if the city main clogged up downstream from your home or the lift station at the end of the run ceased to function. And every backed up from there. Even then you wouldn't get a back up unless you were the lowest house on the city branch.
If you wish to be sure I would find out exactly where my house was located from the lift station. Regards, Tom

Thanks Tom. Yes my basement was built with a floor drain along with all of my neighbors. I think you gave me the common sense answer I was looking for. If there is a main line clog downstream it will backup into somebody else's basement first since my house sits up higher than all the other houses around me (including the houses downstream). With that being said the only issues I would have to worry about would be a main line clog between the house downstream of me and my house since I would be the next line upstream but even with that I believe the houses on the other side of the street tie into the same main waste line and they sit ~5-8 feet lower than my house. Or a clog in my line leaving the house tying into the main line (and I don't have any trees in the path of the waste line so no issues with roots breaking my pipe. So I think I will probably be OK not installing a backwater valve.

Hey Mike,

The reason I asked about the floor drain was to find out if the main had ever a history of backing up into your basement. It hasn't so I think you're making the right choice. Good luck, Tom