An unpleasant smell from drains or the sewer can quickly spread through your home and make everyday life uncomfortable. The problem often stems from small faults in the drainage system, lack of maintenance, or dried-out traps – but fortunately, you can prevent and remove these odours with a few simple steps. Here’s a practical guide to keeping your drainage system healthy and odour-free.

Why do odours occur?

Odours from wastewater usually come from sewer gases escaping through the drainage system. These gases contain sulphur compounds that smell strongly of rotten eggs. When everything works properly, the gases are kept out by water traps and sealed pipe joints. But if something goes wrong, the smell can find its way indoors.

The most common causes are:

• Dried-out traps – especially in drains that are rarely used, such as in guest bathrooms or utility rooms.
• Leaking joints – small cracks or loose seals can allow odours to seep out.
• Blocked drains – build-up of grease, hair, and soap residue can cause bacterial growth and bad smells.
• Ventilation issues – if the vent pipe is blocked, pressure changes can push odours up through the drains.

Check and maintain your traps

The water trap is your first line of defence against odours. It acts as a small water barrier that prevents sewer gases from entering your home. If the trap dries out, the barrier disappears – and the smell escapes.

• Pour a little water into drains that are not used often.
• Add a small amount of cooking oil on top of the water to slow down evaporation.
• Clean the trap a couple of times a year to remove grease and debris. You can easily do this by unscrewing it and rinsing it under the tap.

Keep your drains clean

A clean drain rarely smells. However, grease, hair, and food particles can quickly form deposits that both smell and increase the risk of blockages.

• Pour boiling water down the kitchen sink once a week to dissolve grease.
• Avoid pouring oil, coffee grounds, or food scraps down the sink – dispose of them in the bin instead.
• Use a drain strainer to catch hair and larger particles.
• If odours have already appeared, pour a mixture of baking soda and vinegar into the drain, let it fizz, and rinse with hot water.

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Ensure proper ventilation

A well-functioning drainage system needs to “breathe.” If the vent pipe on the roof becomes blocked by leaves, debris, or even bird nests, pressure in the pipes can change, causing traps to empty and odours to spread through the house.

Check regularly that the vent pipe is clear. If you live in an apartment building, contact your building management or maintenance team if you suspect ventilation problems.

Pay attention to basements and floor drains

Basements and utility rooms are particularly vulnerable because the drains there are often used infrequently. Dried-out floor drains are a common cause of bad smells.

• Pour water into floor drains every month.
• If the smell persists, check whether the trap is damaged or leaking.
• In older homes, it may be necessary to replace worn-out drain components to ensure a proper seal.

When you can’t solve the problem yourself

If the smell continues even after cleaning and checking the drains, there may be a more serious fault in the drainage system – such as a cracked pipe or a defective trap under the floor. In that case, you should contact a qualified plumber or drainage specialist. They can carry out a smoke test or camera inspection to locate the source of the odour.

It may seem like an expense, but a professional inspection can prevent bigger problems and ensure that your home remains healthy and odour-free.

A healthy drainage system improves indoor comfort

A well-maintained drainage system is not just about comfort – it also affects indoor air quality and hygiene. By maintaining traps, cleaning drains, and ensuring good ventilation, you can avoid most odour problems and extend the lifespan of your wastewater system.

Small routines make a big difference: a little water in unused drains, a weekly flush with hot water, and attention to any changes in smell or sound. That way, you can avoid unpleasant surprises – and enjoy a fresh, comfortable home.