The back of my house faces directly west and there is nothing behind it except for fields and the Yorkshire Dales. When the wind blows from the west we get the most awful pong in the en-suite shower room. It is definitely the unmistakable smell of raw sewerage. The en-suite consists of a shower, sink and toilet. I don’t think the pong emanates from the toilet as there is water in the bowl. A bit of sniffing around (literally) suggests that the aroma is coming from the shower drain. The house was built in the late 1980s so has a single stack drainage system with the stack venting above the roof line.
The only explanation that I can come up with is that the wind blowing across the top of the vent pipe is somehow sucking the water out of the trap on the shower drain thus letting the smell of the sewers into the house.
Does this seem reasonable or is there another explanation? Regardless of the cause, is there anything I can do to prevent it. It really is an appalling smell.
Cheers
Dr P.
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Maybe investigate fitting a Durgo valve, (an air admittance valve)
These are normally fitted inside the property and most searches will say ONLY inside but.
External Air Admittance Valves
The FloPlast External Air Admittance Valve is the world’s first and complements the existing array of internal air admittance valves available in FloPlast’s Soil & Waste range
This would fit over the open top of the stack.
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You might be able to fit a deeper trap or traps, or fit a valve to the vent.
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That seems like a reasonable explanation.
Sinks and basins usually work on about three inches of water seal in the U-bend.
Showertraps may only have 3/4" of water seal so will be more susceptible to winds removing that seal.
You could see if there is room to fit a fullsize trap.
Edit - FT beat me to it. I must learn to type faster.
Last edited by: crocks on Thu 1 Apr 10 at 17:23
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Most of this valve stuff is beyond me, but how about putting an ordinary sink plug in the shower drain?
There's one factory fitted to my caravan in leafy North Yorkshire, although I removed it after standing on it a couple of times - ouch.
A plug might at least confirm the source of the smell and provide a temporary cheap fix.
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IIRC most showers have a flush drain cover ( saves toe damage).
So the only type to use would fit would be the large flat bath bath plugs but they need water pressure to keep them in place.
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Makes a strong case for the old adage about not "doing anything" on your own doorstep....
:-)
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You could always bung up the drane with a pair of socks.
Oh, sorry, that's Molesworth's job.
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Henry,
The shower in the caravan has a plughole with a recess, albeit a shallow one.
An ordinary plug will do the job and that was what was fitted, although it would be easy to knock it out, and I don't suppose the seal can be as good as a traditional bath plughole.
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Hi
You can get anti-syphon traps to prevent this problem. They let air in if a vacuum occurs downstream of the trap.
There are a few examples on this page: www.bes.co.uk/products/124.asp
HTH - R
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It's all been covered here. You don't need me. I'm going back to me glass of wine.
Yours...............dejected........................MD. zzzzz
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Don't feel bad about it MD. We've just been doing our best to hold the fort while you've been out doing real work.
Have another glass, I'm sure you deserve it.
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OK, but I guess you swine's will make me pay for it later!!!!!!0:)
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Thanks for all the replies guys. I'll take the bottonmw bit off the shower and see if there is space for an anti-syphon trap. Seems easier than putting a top on the stack.
The plug hole is flush with the base of the shower so not much chance of a plug, elegant idea though.
Thanks
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Maybe worth a try of this
shop.packyourbags.com/acatalog/t_universal_sink_plug.jpg
might just work before you start the big dig.
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The anti-syphon device doesn't have to be on the trap itself... you can get an air admittance valve that will fit anywhere in the pipe run. I have a couple in the plumbing box at the moment.
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>> The plug hole is flush with the base of the shower so not much chance
>> of a plug elegant idea though.
Ours is the same. I bought a rubber bath plug which is intended to sit over the bath drain and I cut off the part which protruded underneath. It now sits over the shower drain to prevent smells.
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If the shower isn't used regularly the water in the trap can evaporate.
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Maybe I think too much, but...
If there is enough vacuum being created in the stack to suck the water out of the trap, then surely it should just suck air into the pipe, which would suck the smell away.... there should also be a significant drop in the toilet water level to match the vacuum being created. Perhaps the smell is being sucked out of the stack, and due to the dynamics of the house being 'down drafted' back into the house via a vent somewhere?
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>> .... there should also be a significant drop in the toilet water
>> level to match the vacuum being created.
The volume and area of the water in the toilet is much greater than that in the shower waste, so that may make a difference.
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Are you sure there isn't a blockage in the drain? Lift up a drain cover to make sure everything if flowing properly.
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>> The house ... has a single stack drainage system with the stack venting above the roof line
The effect you're suffering from is called "wavering". My college textbook expands thus:
A trap (in the waste pipe from a sink, basin, bath or shower) may lose its seal through natural causes, including: (...)
Wavering: Wind pressure across the top of the soil and vent pipe, particularly in exposed locations, causes the water in the trap to produce a wave movement and wash over the weir of the trap. This does not happen often, and can be avoided by fitting a 90° bend or a cowl to the top of the vent pipe.
Examples of these parts (links to Screwfix) include:
90° bend bit.ly/bxF6D7
vent terminal bit.ly/b6iSmb
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A Plumbing Question! - henry k
