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Extreme Back flow problems

80 year old/gut renovated 6 years ago, 7 family house in Gowanus Brooklyn. Extreme back flow problems in the basement whenever there are extreme rains. I understand our proximity to the Gowanus Canal is a major part of the problem, however our neighbors building does not have any back flow problems. The roof drain is not connected to the house trap. We have gone through 5 plumbers and none have been able or seemingly willing to help. There is a check valve in the main sewer line, but it is obviously not working or is not capable of handling the volume of water coming out. I have a bathroom in a finished basement that back flowed for 20mins yesterday. There is a check valve in the main house trap, but it is either not sufficient or it doesn't work. Is a backflow preventer more reliable?

C of L Tech
Re: Extreme Back flow problems


Whatever you do, do NOT put a backflow preventer on your outgoing sewage line!:eek: These devices are in no way designed for this purpose. In many cases, they would likely cause more problems than they would fix. I am IAPMO certified in backflow testing, repair and surveying. Unless you are using some sort of lift station involving booster pumps that could achieve the PSI necessary to actuate a backflow prevention assembly, you will basically be installing a very expensive plug in your sewer system. A weighted check valve would be the best option in your case. It is most likely that the existing check is no longer functioning. Be sure that when the new valve is installed, you have a functional clean out placed on either side of the check. This will allow the line to be serviced is case of a plug either up or down stream of the check. You say there is a canal near you. Do you know if your area runs on a combined (storm drainage & sanitary sewer together) system? If so, the check should remedy this issue. However, if you are running on seperate systems, it is likely that the problem lies with your under drain system. This system is known by many names; a french drain, weeping tile, perimeter drain etc... If this is the source, then the problem is a bit more tricky. Firstly, have your local water company come by and do a chlorine test on the water coming in. If it has chlorine in it, then it is treated water (assuming your local water purveyor uses chlorine) and likely your sewer system backing up. If the water company can't/won't do this, a simple pool or fish tank test kit is an easy DIY solution. just be aware that most chlorine test kits (aside from a $500+ Colorimeter) will give a false positive if done incorrectly or left to sit too long. If no chlorine is present (or detectable) your problem probably is ground water. A (functioning) check valve will prevent water from coming up the underdrain lateral. However, if the check is shut and preventing water from coming into the building, it may also prevent the buildings own drainage system from operating properly. You may need to install a sump/booster pump to counter the backpressure caused by the backing up underdrain. The best option (depending on your areas codes) is to daylight the effluent line from your sump pump, and let the street drainage take care of the problem. Hope this short book :-) helps!

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