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Does rough plumbing cause basement flooding?

Posted by schada (My Page) on
Wed, Apr 18, 07 at 13:55

I am in the process of finishing the basement and planning to provide rough plumbing for future bathroom. Since our sewage outlet is 2 feet about the ground I need to go with pit and sewage pump. I need to cut the concrete to install the pit and drainage pipes. Does this cause any flooding problem in future? Does any one has experience with it? Since I am cutting the concrete, even though I am going to fill it up, does the concrete has same strength as before? With so many flooding news around NJ, I am very hesitant to cut my floor. Your suggestions are greatly appreciated.

Follow-Up Postings:

RE: Does rough plumbing cause basement flooding?

Do you have one pit already? If yes, then it should be for the foundation water.

Your rough-in for a bathroom MUST go to an ejector and since you say the outlet from the house is 2 feet above the floor, you will not have any water back-up through your rough-in. Pump it up higher than the 2 feet though before entering the sewage line.

Provided you already have one sump for the foundation, hydraulic pressure from ground water will be relieved through the foundation tiles and into the pit with the water being pumped back outside. Therefore no water will enter through the concrete cuts. If you're finishing the basement, I would recommend a back-up pump for this pit in the event power or the main pump fails.

If you do not already have a pit for the foundation or have combination sewage/storm sewers, you best get a local, professional evaluation.

RE: Does rough plumbing cause basement flooding?

Thanks for the advise. There is a French drain around the walls and connected to a pit. I need to install submersible battery backup sump pump. I am planning the roughens such that the bathroom sewage will be pumped almost 7 feet high to the ceiling and rundown almost 15 feet before joining the main sewer. I will make sure the pipes are pitched right. My only concern is since the ground water levels are high in our area, is there a possibility of leaking the water through the concrete cuts I made for rough plumbing. Thanks again for your advise.

RE: Does rough plumbing cause basement flooding?

Sounds like you're on the right track. In effect your foundation tiles (or French Drain) will capture any water above its level lowering the water table. Is the French Drain on the outside of the foundation? If yes, I believe your concrete cuts will be dry. If inside, I would seek a qualified local opinion. No idea about them as all here are exterior alongside the footings and tiled into a sump pit which is inside. Water only enters the basement if a tile has failed or the electricity goes out.

Make certain your plumbing is vented properly. That is critical.

RE: Does rough plumbing cause basement flooding?

Since a pit for a sewage ejector is completley sealed from everything, there should be no water entry.
Remember it needs a vent and some codes prohibit joining this vent to any others. It must run all the way to the roof all by itself.
Ejector pumps can move a lot of water quickly (they need to be large enough to move debris) so the venting is not small.

RE: Does rough plumbing cause basement flooding?

The concrete floor is not a barrier against water unless it was specifically waterproofed, so cutting it should not create an entry for water.

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