Re: Basement flooding even after new check valve installed...
Posted by HPYC on 2017/5/11 11:20:46
One other potential source of flooding: when the sewers are full & your check valve is up, there's nowhere for the storm water from your roof to exit your building. (I'm assuming here you don't route your storm water directly out the alley or the front). I've had this issue from places where a high water table couldn't possibly be the culprit.
Totally agree. Other sources when the check valve is closed include waste water from inside the building (especially if there are multiple units in it), and sump pump discharge. When the city sewer is full and pressurized, there is nowhere for this water to go except backward, where it looks for the path of least resistance - which could be a floor drain, toilet, tub or any other opening in the line between you and the sewer. Tell your upstairs neighbors not to flush when it's raining ;)
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