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Why do my drains smell?

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 Why do my drains smell?

The modern plumbing system is a wonderful thing. It helps to prevent disease, ensures our homes stay sanitary, efficiently removes waste and sewage, and generally deals with the messy side of human existence. Occasionally, however, this finely tuned system can fail, potentially causing bad odours, and worse, throughout our homes.

Why do my drains smell?

Getting to the bottom of the problem of why your drains are smelly may require some investigation and but can often be an easy issue to fix. Don't hesitate to contact your plumber for some professional help if the odours remain as the problem may be more involved.

Dry P trap

If you haven't used the sink, bath, or shower in a while the water in the P-trap under the sink can evaporate and allow sewer smells to travel up into your home. Run the tap for a few minutes to flush the drain and refill the P trap.

If the drain is still stinky after flushing and refilling the trap, place a bucket below the sink, carefully unscrew both sides of the U-pipe, remove anything blocking the drain and give it a scrub with a bottle brush or old toothbrush to dislodge sticky or greasy residue. Carefully replace the U-pipe and refill the trap.


A build up of fat, oil, grease (FOG), hair or food scraps can clog drains stopping them from flowing freely, sometimes causing a foul smell.

To prevent this occurring use a drain strainer to stop food and hair from being washed down the drain pipe and dispose of fat, grease and oil in the rubbish.

Not so flushable wet wipes

Another cause of drain clogging, particularly from toilets, is the so-called 'flushable' wet wipes. Your sewage drains can quickly become blocked with these wipes which don't break down like toilet paper but build up in the pipes causing costly plumbing issues.

If your family uses 'flushable' wipes make sure they throw them in the rubbish bin rather than down the toilet to protect your drains.

Damaged pipes

Even a small crack in a drain pipe may cause issues which can prevent plumbing systems from getting rid of the nasty drain odours. Contact your plumber if you suspect your pipes are broken, cracked or damaged in any way.

Faulty plumbing installation

If your drains have been ponging for a while despite many attempts at drain cleaning and clearing to remove the smell, there may be an issue with poor installation or faulty repairs. Despite the simple appearance of the pipes and drains under your home even a small defect cause issues.

This is definitely one for your plumber to investigate.

Garbage disposal

A build up of food waste in the garbage disposal system can very quickly lead to a stinky kitchen. Ensure a generous amount of water runs through the system after each use to flush away all the food debris.

Regularly clean the disposal unit by running ice cubes and large chunks of lemon through it, finished with a generous rinse of hot water.

Dirty dishwasher

Food scraps left to rot in the bottom of a dishwasher can create an odd smell in your kitchen which can be confused as a drain issue. Clean the drain covers and strainer every few days. Most are easily removed and cleaned with a small brush and warm soapy water.

Leave the dishwasher door ajar when it's not in use to prevent mould and mildew growth and to allow the machine to dry fully between washes.

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