Backflow Preventer Flapper doesn’t allow flow

[Chuck Rawas]

Hello

I recently had a backflow presenter installed by a licensed plumber along with a sump pump that’s located inside a big barrel. I’ve found that the flapper of the backflow valve hardly ever opens when I flush a toilet or run a sink or whatever. The only time I see it open is when I fill up the basement bathtub high enough for water pressure to build and then the flapper opens somewhat. Not even halfway. Is this a problem or is this how it’s supposed to work? Seems like poor design because the flapper seems too heavy and the toilet flushes are not powerful enough anymore in this area with water conservation measures in place. Anyone have this issue?

 

[Reach4]

I am not a plumber.

I presume that the water is not rising to the top of the flapper as you watch.

The problem is that with time your flapper-type valve leaks enough to keep up with light loads without the flapper moving. It's almost predictable, and its a deficiency of the design. Sometimes a valve like that is called a normally-closed valve. The problem is that as debris builds, water coming from the sewer will not be stopped by the flapper, but it may get slowed down.

The kind that work much better are normally open. A gate floats up as the water level rises to block the sewage. If you want to read about this, try this search in a search engine: backwater "normally open"


However your flapper type can do a good-enough job it it feeds from a big vented sealed pit. If the water backs up in the pit, the grinder pump (not a common sump pump) kicks on, and the waste is injected out down stream of the flapper valve. Sewage is pressured toward the street, but it is also pressured backwards through the flapper due to unwanted but present leaking. However the pump can pump faster than the leak. Plus the pressure helps drive the flapper closed some. If the power continues to work, the city sewage and even your own sewage does not fill your basement.

Does this sound like the system you have?

Often the pit is buried in the front yard with the pump and valve inside. It is covered with a tray that contains grass, and can be mowed with the rest of the grass. Lift the tray out to service via a concealed manhole. These can be be built with a normally-open backwater valve. Those will function even if the power goes off. Some amount of house waste can be stored in the pit until the power is restored.

 

[Sponsor]

 

[hj]

There is NO reason a backflow valve would be installed in a drain to a pit with a pump in it.

 

[Reach4]

There is NO reason a backflow valve would be installed in a drain to a pit with a pump in it.

A backflow valve can let the sewer drain by gravity in non-backup times, even if the pump is not working for some reason.

.... http://www.floodexperts.com/
They are not the only provider, but are respected. They put the pit in the yard.

 

[Chuck Rawas]

I’m not really sure what you mean. My valve is the one that’s always closed. I do know that. And being that the flush systems are so weak nowadays, it almost never opens with a standard flush.

 

[Reach4]

I’m not really sure what you mean. My valve is the one that’s always closed. I do know that. And being that the flush systems are so weak nowadays, it almost never opens with a standard flush.

I could clarify some point if you like, but if you are not seeing meaning at all, that would say we don't communicate.

Clearly the flapper valve is passing water from hand flushes, and other water use. Otherwise water would back up. I think you are opening a port on the downstream side of the valve and watching the flapper. You don't see movement. Yet when you run a sink at 1 gpm, you can spit bubbles on the flow, or lightly sprinkle flour if you prefer, and see that there is indeed flow through the valve that looks closed.

I think you are implying that your pump is not in a pit that outputs through the flapper, as I was suggesting. Instead you may be describing a ground water sump pit with a pump, and it is unrelated to the brass flapper valve. Is the only connection between the pump and the flapper that they were installed by the same plumber as parts of the recent project?

 

[Chuck Rawas]

My pump is inside a barrel type contraption. Any water that is not able to flow freely to the outside sewer, backs up into this barrel and when the barrel gets full past a certain point, the pump activated and pumps out the water to the street. Does that make sense?

 

[Chuck Rawas]

And yes i do see flour padding through. It’s small enough that it goes around the flapper. But what about waste or toilet paper? That’s not small enough to go through the little space the flapper makes.

 

[Reach4]

I presume

My pump is inside a barrel type contraption. Any water that is not able to flow freely to the outside sewer, backs up into this barrel and when the barrel gets full past a certain point, the pump activated and pumps out the water to the street. Does that make sense?

Yes. The sump and sump pump are unconnected to the sewage and flapper valve.

And yes i do see flour padding through. It’s small enough that it goes around the flapper. But what about waste or toilet paper? That’s not small enough to go through the little space the flapper makes.

Eventually, the build-up would probably burst through with a big flapper move while you are not watching. I have a friend who put a clear cover on his path, and ran a camera. I never saw it. It was there to watch for water rise, but seeing flow was a side effect. His pre-overhead-sewer action was to stick an inflatable ball into the pipe for the event. Not even using a Cherne test ball, which would have been the much better tool. But the overhead sewers fixed all of that effort and anxiety.

Your current system is not going to stop sewage backups, I am afraid. Do consider an insurance adder for sewer backup. Normal homeowner policy usually excludes that without paying extra.

If you want to really never have sewer backups into your basement, overhead sewers are the gold standard. But there are better valves than your classic normally-closed flapper. They do need a bit of an elevation drop, so you may need to have a longer stretch excavated to get the drop. If you are the lowest house in the area without good defenses, things will get worse -- presuming they don't redo the sewers in your area.

Now if the neighbors are doing as you are doing, and moving ground water to the curb rather than putting that into the sewer system, that can help. What motivated you? Did the city take steps to make sure that your sump pump was not going into the sewer? That can help for sure if they get everybody to make the change.

 

[Chuck Rawas]

Last summer I had a huge backup from a storm. This has now saved me because any backup that is not container by the backflow preventer, flows into the barrel and is then siphoned out to the street as opposed to rising up in my basement.

Not all my neighbors have a check valve and sump pump. It’s not required in my area. I only put it last year because of the backup that I had