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Basement Floor Drain-nasty back-up

My husband and I own a bungalow built in 1922. We know that we have combined sewers (the rain water and sewage flow through the same lines). When there is a hard, fast rain the basement floor drain takes on water and...ummm other things that shouldn't be on a basement floor.
I actually work in preservation and have asked a few of my co-workers about this problem. They have told me that we need a stop-check valve for the drain to alleviate this horrible issue. It just happened the other day (we're in Indiana and had a few nasty storms) and we had about 4 inches of water in the basement. Thankfully it recedes quickly but the mess it leaves is beyond nasty as you can imagine.
So, my questions are...-has anyone else dealt with this issue? -what is the best solution to this problem? -if we need a stop-check valve is that something that we can do ourselves or do we need to hire a plumber?
Any help would be greatly appreciated!!

Re: Basement Floor Drain-nasty back-up

It's very possible that the original foundation perimeter drain is tied into the main drain of the home which is discharged to the city sewer system. In cases the older homes may have had the downspouts enter the home and drain into the same system and usually are not allowed to do this any longer. Depending on your setup the original foundation drains likely run to the floor drain sump then empty into the main drain discharge out to the street.

When it rains heavy all this water from the perimeter drainage system combined with the other sewage from your home is being discharged to the city sewer system at the same time the street drains ..... all this combined overwhelms the system.

There are different types of back flow prevention valves that are used in different locations.
The simple type is one that fits into the floor drain .... a "ball" type which allows water from the top side to push open the ball and allow the drain to operate normally. When water flows back up from the underside of the ball it closes the drain preventing back flow. The problem is when the main sewer line outside is overwhelmed it will back up into your home filling the pipes before this ball closes. In extreme cases if you have a bathroom in the basement you may experience flooding from the toilet , shower or sink drains but not from the floor drain.

The more effective one is the type with a one way flap that is installed in the main sewer pipe ... either inside the home just before it exits the foundation or at the point of connection to the city's sewer line. Discharge leaving the home will open the flap and back flow will close the flap. In the event the city's sewer system is overwhelmed it will only back up as far as this preventer valve and not fill the home's internal piping.

The problem is if the city's sewer system is overwhelmed and is backing up when you flush your toilet the waste can't be discharged ... it's got nowhere to go except back into the homes interior piping.

Another issue is when the the sewer line is overwhelmed and the backflow valve is closed the perimeter drains will still flow into your floor drain and have nowhere to go. The added step would be to install a sump pit with a sump pump to collect the water from the perimeter drains as it overflows and discharge the water outside.... as shown in this diagram.

Hope this helps.:)

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