Just recently has storm backwater flood my basement through the 2 floor drains. A few weeks ago when my neighbor was draining his backyard pool I noticed remnants of slight flooding, but last night during the storm it flooded the entire basement by 2" with water gushing up through the storm drain. It eventually started draining again after about 15 minutes and the water flowed back into the drains.

Now I'm trying to avoid a repeat - can I install the one-way floor drain flood guards as protection? If so, will the water escape through the rest of my drainage system and flood upper floor drains? Or, will the water just "find its level" and stay low blocked off and isolated? Should I get a check valve at the source connected to the sewer?

How do I know if the overflow was from the roof water coming down or from the city sewer main? enter image description here

1 Answer 1


If that's your plumbing layout, presumably it would overflow at the basement laundry sink if it was going to overflow with the floor drains successfully valved.

Whether it would will depend how much pressure there is - while your flood was only a couple of inches, it was spread out from two floor drains across however much basement area it flooded, so there might well have been more than 2 inches of back pressure if contained in a pipe rather than allowed to spread out.

Assuming your drains connect to a municipal sewer, requesting the agency responsible for maintaining that sewer to correct the problem of it backing up during storms (perhaps indicating a partial blockage/collapse or need to be cleaned, or infiltration [storm water getting into the sanitary sewer] if it's not supposed to be a combined sewer/storm sewer) would be the best solution.

  • I'm in Queens NYC, the city folks came out and said they checked the manhole and it was clear - however that was the next morning and hours after it cleared. Should I install a backflow valve or a cinch valve at the sewer main instead? Sep 11, 2020 at 22:59

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