Waste Pipe Problems - Intermittent Smell

[MVincent]

Hi,

We have recently bought a new (ish) house (2008 build). In the main bathroom every now and then there is a smell like a sewer. At first we thought it might be the Jacuzzi bath jets etc not being properly treated after use by the previous owners but it was cleaned with the correct treatment and the smell occurs so that has been ruled out. In the bath room there is a shower, toilet, sink and bath. All the pipe work is either boxed in, behind the tiled in bath or runs into the stud work.

The SVP stack is the internal type and is boxed in the corner of the room with the toilet connecting straight into it. The sink seems to run into the studwork and then I assume connects up with the bath and then runs into the stack. The smell only seems to occur when the sink or the bath is being emptied I have also noticed that the bath seems to be draining very slowly as of late. The smell doesn't seem to happen when the toilet is flushed though.

Sorry about the poor description. Would you have any ideas of what might be causing this or where to start investigating?!

Thank your for your help

 

[Keefy]

Does the water bob up and down in the toilet pan when it's windy outside? I'm asking this because you say the smell is intermittent but disappears when you flush it so it may be losing it's trap seal and allowing gases to enter the room. Also, does your bath or basin make a glugging sound as they've finished draining? If so, anti-vac traps may need fitting in place of your existing ones. Of course it could be a number of other reasons but these are possibilities to consider first.

 

[kay-jay]

Emptying the bath is syphoning the water from the basin trap is my guess. Next time you can smell it dip a long screwdriver or a straw down the plugholes check to see how much of it is wet. The one with the least water in it will need the trap swapping for an anti vacuum trap.

 

[plumber0808]

The basin waste is probably teed into the bath waste.
When letting one go it siphons the other trap out allowing smells to enter the bathroom.

 

[thompsonbrown]

Agree with above anti-vac trap.

 

[MVincent]

Thank you all for your quick responses! As soon as the smell comes I will check the level in the trap. I have attached a picture of the existing trap - is this just a standard trap? With regards to getting an anti-vac trap is there one you would recommend or all they all pretty similar?

Thanks again for your input its been really helpful!

 

[Griffo]

Thats not an an anti vac trap its a decorative Chrome trap by the look of it.