Any ways to prevent backflow of sewer water into the home?

Question

Hello all,

I mentioned on a post today morning regarding sewer line backup that happened 2 times in a year at a rental property we own.

https://www.biggerpockets.com/forums/52/topics/294...

I would like to ask if there are any mechanisms available that can be installed in the sewer line, to prevent backflow of the sewer water into the home? If so, how do they work and what would be an approximate cost to install that?

Thanks.

- Andy.

Wayne Brooks · Answer

All back flow preventers I know of are for (clean) water systems under pressure, not sewer. But, more to the question at hand, if such a device did exists, it wouldn't help the problem.  Your overflowing of the down stairs toilet didn't come from sewer water flowing back into the house from the line....it came from sewer water from the second floor that couldn't exit the house due to a clog.  Water seeks it's own level, so when you have water trapped in the system, head pressure is going to push it out the lower opening, the first floor toilet.

Nathan Gesner · Answer

They make what are called backflow preventers. They are very common and very inexpensive. I think you can buy one at Home Depot for under $40. You probably need a plumber to install it.

Search on Google and you will find tons of info.

Thomas S. · Answer

Simply do a search on google- septic backflow prevention.

Edward Regan · Answer

Sewer Backwater Valve

A backwater valve installed professionally on a house drain  can be a permanent solution to waste water backing up from heavy  rainfall inundating a public drain system. A backwater valve should  always be installed in front of the house trap  on the street side of the trap. This would prevent a public sewer  system from backing up into a house. Another less advisable option if  there are plumbing fixtures in the basement such as a toilet or a even a  full bathroom or kitchen is to install an individual backwater valve  for each plumbing fixture.

http://www.balkanplumbing.com/backwater-valve-back...

Johann Jells · Answer

This won't help but I can't stand not clarifying, what goes on the 4" sewer line just inside the foundation is called a Check Valve, not a backflow preventer. It keeps a flooding sewer system out of your basement. But as said, if there's an obstruction and you keep using water, the house system will fill till it finds an outlet.

Lisa Duke · Answer

I used to build custom homes, so I have some understanding, but it was my amazing husband (who has been a licensed master plumber for over 35 years) who helped me with this answer.

There is no such thing as a back flow preventer for a sewer line.

Why would you put a back flow preventer on a gravity flow system? Just think about it : )

If the second floor sewer line was clogged, it would come up into the tub or shower there (flood rim on a shower is 4") and then overflow the toilet on the second floor also, not the first floor.

You need to have a licensed plumber check your yard line for any obstruction such as roots. A cracked PVC line will attract tree roots. Cast iron was rough on the inside, installed in only in 10' sections and the joints would break down and again, roots and dirt would clog--it hasn't been used since the '70's.

Even with paper towels and facial tissue, they should go through, unless they are catching inside the line in the yard somewhere.

Most people know not to flush such items down a toilet, but even so, a compromised yard line will continue to be a problem.

Andreas W. · Answer

@Andy K

I have never heard of a device like that. You need some kind of flapper valve to prevent return flow, but it is useless if your tenats keep running water once the back up occurs. If the clog occurs at the same location repeatedly, there is the chance that you have a sewer line problem next to a tenant problem. A 4 in sewer line should be able to handle a few paper tissues. Since you covered the bill the first time, they think you will cover it again, and they just don't care. If you can, get new tenants and have the current ones pay as much as possible. Also,  have your plumber run a drain camera to see if the sewer line has problems. Of course, you will lose all arguments if you do find issues.

Any ways to prevent backflow of sewer water into the home?

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