How to Get Rid of Drain Smells

The smell itself is a good clue. A sour, rotting-food smell from the kitchen sink usually means fat and food waste coating the waste pipe and trap. A musty or eggy smell from a shower, bath or basin is usually hair and soap scum caught just below the plughole, where bacteria break it down.

A strong sewage smell is different. It can mean the water seal in the trap has dried out – common in a spare bathroom or a property that has been empty – or that there is a problem further down the system. If the smell is from outside drains, manholes or several plugholes at once, or if water is backing up, it needs a drainage professional rather than cleaning.

Start at the top. Remove the plug, strainer or pop-up stopper – most lift out or unscrew – and clean off the slime and hair with an old toothbrush and hot soapy water. In a bathroom basin, the pop-up rod usually has a small nut behind the basin that releases it.

Use a cheap plastic drain hair-removal strip (the barbed kind) to pull out hair from shower and bath drains. It's an unpleasant job, but it removes the main source of the smell more effectively than any product.

For a kitchen sink, run very hot water with a good squeeze of washing-up liquid to help shift grease. Then pour in around half a cup of bicarbonate of soda followed by a cup of white vinegar, cover the plughole for ten minutes and flush with hot tap water or a kettle of water that has cooled for a few minutes.

The fizzing doesn't dissolve blockages, but it helps loosen film and leaves the drain smelling cleaner. Enzyme-based drain cleaners, used overnight, are a good option for regular maintenance because they digest organic build-up without harsh chemicals.

If the smell comes back within days, the trap under the sink probably needs emptying. Put a bowl underneath, unscrew the plastic bottle trap or U-bend by hand, tip out the contents and wash it in a bucket – not in the same sink. Check the rubber washers are seated properly when you screw it back, then run water and look for drips.

Do this only on simple push-fit or screw-together plastic traps. If the pipework looks old, glued or difficult to reach, leave it to a qualified tradesperson.

Every sink, shower and bath has a U-shaped trap that holds a little water to stop sewer gas coming back up. In a guest bathroom, holiday let or property between tenancies, that water evaporates after a few weeks and the smell comes straight through. Running each tap for a minute fixes it.

Landlords and agents often notice this at the start of a new tenancy. Our guide to cleaning between tenancies includes running every outlet as part of the turnaround.

Most stubborn drain smells start with what goes into the sink. Keep these out:

Strong caustic or acid drain products work by dissolving organic matter, but they're hazardous to skin and eyes, can damage some pipes and finishes, and are dangerous if mixed with other cleaners. If you use one, follow the label exactly, ventilate the room and don't plunge the drain afterwards in case it splashes. Our guide to cleaning products you should never mix explains why.

If a drain stays slow or smelly after cleaning, or several fittings gurgle when you run water, stop and call a drainage specialist.

A weekly clean of the plug strainers and a monthly flush keeps most household drains smelling fine. Many regular cleaners include wiping plugholes and overflows, and a deep clean usually includes removing hair and scum from plugholes. If you have a particular problem drain, mention it when you ask for quotes.