Re: Basement flooding even after new check valve installed...

Posted by jcneighbor on 2017/5/11 16:30:03

brewster wrote:
Just to clarify with a little physics, water seeks its own level. When your upstairs neighbor flushes, the level in the drainpipe will not rise above the level of the street sewer, it WILL drain, even if you have a check valve. If that sewer level is above your basement toilet or sink, then you have problems already, but they can become shittier.

As for BK, the trendy areas around Park Slope are on relatively high ground.

I was actually waiting to see if there were any other crazy theories besides the rain/gutter runoff or the "don't flush the toilets" or if someone intelligent would chime in with a reality check. Brewster wins!

And I'll add a bit more: It's all about the weight of water in a column. Let's say your vertical sewer drain pipe (or gutter downspout) is 4" in inside diameter. That means that for every foot of vertical rise there is a weight of 5.45 pounds. Now flush a toilet on the ground floor (above a basement) and you're draining about 10 feet down to the sewer line out to the street. Call it 55 pounds of pressure. Ain't no way, NEVER, the main sewer line is even remotely close to that pressure. Your check valve will happily pass it through-

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