Smelly Drains

[rjt20000]

I've recently had building works completed (2 months ago), which included durgo valves for the 1st floor bathrooms (there was an SVP previously). Am now getting sewage smells emanating from the external drainage (which has a 70m run from the house to the mains) and is noticable in the garden, into the downstairs wc. I don't know if it's related to the durgo valve, but the external pipework seems to be running ok (I hosed down through the manhole). Any ideas as to what's causing the problem, and how to solve it? Thanks

 

[Hugh Jaleak]

Durgo valve is an 'air admittance valve' or AAV. Does what it says on the tin, allows air in. It wont however, let air out, which could be where the problem lies.

You should have at least one vent on the system, preferably at the highest point of the drain. If the vent has been removed then there is no facility for any positive pressure in the system to be released where it wont cause a problem. Replace the vent!

 

[Nige F]

Dead right Hugh . And don`t be fooled by "air tight inspection chamber " lids - they`re not

 

[rjt2000]

Thanks for that. I'll investigate, but do you think it would have taken a few months to start smelling if it were the durgo valves?

 

[Richard C]

If the foul drain has no other open vent then gasses cannot escape & the drain will slowly pressurise until it starts to force its way part the weakest seal it can find.

Another thing to consider is that there is very likely to be methane gas present so don’t go throwing fag ends down the bog or smoke when you lift the drain hatch or there could be a loud bang & one hell of a mess!

 

[rjt2000]

I'll lift the lid to the rodding point down the garden then