Drain smell coming from bathroom sink

[julie1]

I have a drain smell coming from my bathroom sink. The water is running away fine from the toilet, shower unit and sink and no water is backing up so I am told it can't be a blockage. We have fitted Hepworth and Durgo valves to the toilet and sink and when this didn't work fitted a different type of air admittence valve to the sink but smells are still coming up. I have had the local water board check the public drains as various neighbours said they had experienced problems either outside or inside their properties yet nothing was found. A neighbour also said the drains were smelling in the road last week. I am told it may be some alternation work done in the road but their is no way of knowing and am at a loss as to what to try next as I am told that other symptoms would be present if I had a broken drain or leak and that internal pipework is likely to be too small to put CCTV camera down. Any suggestions gratefully received.

[stoneyboy]

julie1,
Drains always smell.
Check you have a trap fitted to the basin if yes try removing the basin trap and cleaning it thoroughly, also clean the waste fitting in the basin. While you are doing this if the basin has an integral overflow you will need to clean this as well.
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