Why does my drain smell?

Drainage hole bubbling. Rapid Drainage, London drainage services

Experiencing foul odours coming from home drains is a very common issue. But why is this happening? A sewer gas leak or mere bacteria could be the cause, as could a clog or something more problematic. This is why you need to investigate the possible cause of any strange scent coming from your drains.

Here are a few of the most common causes of smelly drains.

Bacteria build-up

A foul scent is frequently brought on by bacteria. Since germs can come from hair, debris, or any other things that may have gotten caught down the drain. This typically happens in indoor bathroom sinks and drains. If you want to avoid this issue altogether, we would advise you to invest in a plug guard. It will collect any debris before it has the chance to go down your drain.

Food waste

Even if you take steps to keep food out of your sink, it is still possible for small particles and other organic debris to enter and collect in your drains to produce an unpleasant odour. Such obstruction can entirely stop the flow of drains or make them evacuate slower than usual. To solve this issue, we would advise you to use a non-aggressive drain unblocking liquid.


If the drain smells even when the water is draining away without a problem and the pipes are clear of hair or other debris, you may have leaky pipes. Hydrogen sulphide, a sewer gas, will escape from leaky pipes in your walls or beneath the shower or sink, giving your shower drain a foul odour. Both perforations in the pipes and sloppy fittings at pipe joints might result in leaks. Over time, corrosion in pipelines frequently can also cause leaks. It is best to leave fixing a leaky pipe to the experts. So in doubt, call your plumber.

Plumbing errors

A plumbing mistake may be to blame for the bad odour if your drainage system is new or has recently had some work done. It can be worthwhile to get in touch with the plumbing company that worked on your drains or another independent plumber to investigate any possible error.


If your sink or shower drain smells musty, it is possible that mould has developed beneath your drain cover. Start by checking if the drain cover is loose, if your drain cover isn’t completely sealed, that little moist area will be the ideal environment for the growth of mould.

To solve the issue you must take off the cover and properly clean the area with mould spray before sealing it. You might even need to scrub the cover if the mould has spread. If cleaning the area does not solve the problem, you might need to purchase a new drain cover altogether.

Collapsed drain

Last but not least, a bad smell that lingers after your drains have been cleared out could indicate a collapsed drain. This may occur as a result of years of negligent drain upkeep or damage and cracks in your pipes. Indicating signs of a collapsed drain is mould or dampness all over the house in addition to a terrible odour, as well as a sunken or moist area in your garden. If you believe your drain has collapsed, you must speak with a drainage specialist as soon as you possibly can to avoid any further damage.

Hopefully, this article has given you a better idea of what the possible causes of smelling drains can be. If you have tried cleaning your drain cover, using drain unblocking liquid, or using a plug guard and still have encountered a smell issue, we would advise you to get in contact with a professional. Visit our blog to learn more about everything drain related and visit our website to book a consultation. If you have any questions, do not hesitate to get in contact with us.