Sunday 25 February 2018


How do we get rid of a foul bathroom smell?

Ted Laverty

Recently we moved in to a house built in 1960 and started to notice a constant and foul smell from the en suite bathroom in the master bedroom. A plumber cut off a drainage pipe outside of the house but it didn't work. We also tried to bleach the toilets and it didn't work either. Can you please tell us what might be the cause and how to fix it? Many thanks, Amy.

There is probably nothing more disconcerting than walking into a bathroom and having to hold your nose as a result of a lingering foul odour. Quite often the source of such smells are obvious and can be dealt with by simply opening a window or spraying some de-odouriser, but in cases like your own the cause clearly needs some thorough investigation.

If you are in any doubt about doing this yourself, please contact an accredited plumber through the Onlinetradesmen service on

Unfortunately any number of things can cause sewage odours in bathrooms. For this reason it is always useful to have a basic understanding of how your bathroom plumbing works, so as to help identify the main cause and deal with it permanently. So here goes . . .

If you look under your sink, you will see a U-shaped pipe that connects underneath it to the drain. This pipe drains the waste water from your sink to a larger pipe in the wall.

One end of this wastewater pipe runs all the way down to the public sewage or septic tank system to expel your waste water, with the other end of it running upwards towards the roof.

The latter connection ensures that all sewer gases are safely vented outside your house. The same system works for your bath, shower and other sinks around the house.

The U-shaped pipe is often called a P-Trap and it uses a small amount of water to create a seal between the vented gases from your waste water pipe and your bathroom. This is what prevents the sewage smell from entering your bathroom. When functioning correctly there should always be a small amount of water in the P-Trap.

So back to the solution for your problem!

As a first step, you should consider looking to see if there is adequate water in the P-Trap to maintain the seal. Run the water for a period and check for any leaks – even the smallest leaks can cause problems here.

Also, if your taps haven't been run for a while this exercise will refill the P-Trap to its required levels.

Seal any leaks with leak sealer available from your local hardware shop or online from If this doesn't work then consider disconnecting the P-Trap to see if there are any blockages – this is often messy work but any residue can cause noxious smells.

If the above actions do not work, it is definitely time to get in touch with an accredited plumber on to investigate further. While many will assume that the toilet is the natural cause for sewage odours, this is far from the case.

If there is water in the bowl it creates the required odour seal – however if it isn't filling correctly there may be a leak in it that requires professional attention. Other causes may be down to blocked vents (with birds' nests, render and paint among the culprits), cracked vent pipes or even poorly installed pipes worth consideration – it has been known for contractors to terminate vents prematurely into attic spaces, recirculating foul odours back into the home.

A qualified plumber can easily identify and correct these issues for you.

For more information on this please contact us on or email

Irish Independent

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