Back Siphoning Problem

[MoonPig]

Hi,

When I flush the toilet in the en-suite, there is a gurgling sound coming from the plug hole of the bath in the bathroom.

It's as if the water flowing down the soil pipe is causing a vacuum and sucking the water from the water trap in the bath. Eventually the water trap becomes empty and smells from the drains come up through into the bathroom.

This has happened since we moved into the house recently, but the house is as it was built with no alterations (approx 16 years old)

The soil stack goes up into the loft and has an air admittance valve in it. I did think that this may be faulty and replaced it, but the problem remains.

It only happens with the en-suite toilet. The toilet in the bathroom has no effect.

Any help appreciated....

 

[xr4x4]

how far away is the ensuite toilet from the soil stack?

 

[MoonPig]

how far away is the ensuite toilet from the soil stack?

Hi, The soil stack is almost right next to the ensuite toilet - the soil pipe goes back from the toilet into a void behind the wall and the soil stack is about 18 inches to the left.

Thanks

 

[Morris40]

you could fit an anti-syphon trap to the bath this is fairly cheap and would solve the problem