7 Reasons Your Sinks and Toilet Emit a Foul Smell

More than just being unpleasant, bad smells from your sinks and toilets can disrupt daily life and create an uncomfortable, unhealthy environment. At home, relaxing might be impossible when your sink or toilet is emitting a foul odour. If you manage a commercial or office space, it can be even worse since bad smells can leave a negative impression on customers and make employees unable to deliver top-notch service. 

A lingering stink coming from your plumbing is definitely worth investigating, and doing so as soon as possible allows you to address the source of the smell before it worsens. In this article, Mains Plumbers presents you with a list of the most common reasons why your sinks and toilets might be emitting a foul smell and what you can do about them.

Blocked or Clogged Drains

Apart from causing visible plumbing issues, clogged drains are also one of the most common reasons for bad odours in sinks and toilets. When debris like hair, food scraps, grease, and soap scum build up inside the pipes, it creates a blockage that traps stagnant water and waste. Over time, bacteria and mould start to grow in the trapped material, releasing a foul smell.

If you notice water draining slowly or hear gurgling sounds coming from the sink or toilet, a clog is probably already forming. You can try to get rid of a minor blockage on your own by using a plunger or a drain snake, but if the clog is deep within the pipes, you may need to use a chemical drain cleaner or call the emergency plumbers Dunedin property owners trust. To prevent future clogs, try using a drain cover so that debris won’t get flushed and trapped in the pipes. Also, avoid pouring grease or coffee grounds down the sink, as these can contribute to the buildup.

Dry P-Trap

That U-shaped pipe under your sink or toilet is called the P-trap, and it serves an important purpose. It holds a small amount of water that acts as a barrier to prevent sewer gases from wafting back into your home or office. If the water in the P-trap dries out, those gases have a free pass into your space, creating that unmistakable sewage smell.

P-traps tend to dry out if sinks or toilets aren’t used frequently. In case you catch a foul smell coming from a sink or toilet that hasn’t been used in a while, try running water down the drain for about 30 seconds to refill the P-trap. A quick flush or rinse is usually all it takes to restore that protective barrier of water and keep the smells from coming back.

Sewer Line Issues

It’s also possible that the cause of the smell is a more serious issue. When there’s a crack, blockage, or misalignment in the sewer line, for instance, gases from the sewer system can back up into your property. These disruptions can be caused by poorly installed pipes, but tree roots and shifting soil can also be blamed for such issues.

When the problem is with the sewer line, the smell will usually be noticeable in multiple areas of your property. You might also notice slow drainage or even sewage backing up into sinks or toilets. Clearly, this is an issue that you do not want to ignore. Should you suspect a sewer line problem, call an emergency plumber. Our plumbers at Mains can identify where the problem is and repair or replace the damaged section.

Bacterial Growth in Overflow Drains

Bathroom sinks and some toilets have overflow openings designed to prevent flooding, but these areas can easily collect stagnant water and debris. When that happens, bacteria and mould start to grow, creating a musty or rotting smell that lingers even after you’ve cleaned the main drain.

To tackle this, you’ll need to clean the overflow opening directly. A mixture of hot water, vinegar, and baking soda usually does the trick. Just pour the solution down the overflow and use a small brush to scrub away any buildup. Keeping these hidden areas clean will help keep your bathroom or kitchen smelling fresh.

Faulty Toilet Wax Ring



The wax ring at the base of your toilet creates a seal between the toilet and the drain pipe. A cracked or loose wax ring will let sewer gases escape into your bathroom.

If you notice a sewage smell near the base of the toilet or see water leaking around it, the wax ring is probably the problem. Do note that it’s not easy to replace a wax ring since you’ll need to remove the toilet; thus, it’s best to call a plumber to handle it quickly. Making sure the toilet is installed securely and the wax ring is in good condition will keep those unpleasant gases where they belong—down the drain.

Poor Ventilation

Plumbing systems rely on vent pipes to release sewer gases and equalise pressure in the pipes. Blockages or improper vent installation can lead to gas buildup, and the gas can then escape through the drains. Poor ventilation can also cause slow drainage and gurgling sounds when you flush the toilet or run water in the sink.

To fix a ventilation problem, you’ll need to clear any blockages in the vent pipes. Some of the more common causes of vent blockages are fallen leaves and bird nests. If the venting system wasn’t installed correctly, a professional plumber might need to modify or replace the pipes to ensure proper airflow.

Mould and Mildew in Hidden Areas

Damp environments are perfect breeding grounds for mould and mildew, which can give off a musty, unpleasant smell. A hidden leak behind the walls or under the floor can lead to the accumulation of moisture, which can then encourage fungal growth.

Do your toilets or kitchens have a persistent musty smell? Can you see dark spots on the walls or ceiling? If you answered yes to one or both questions, then you probably have a mould problem. Fixing any leaks and improving airflow with a dehumidifier can help stop the mould from returning. If the mould has spread, you may need professional remediation to clear it out completely.

Mains Plumbers Can Help You Resolve Sink and Toilet Odours

Bad odours from sinks and toilets can stem from a variety of issues, from minor clogs to more serious plumbing problems. Catching the problem early and taking the right steps to fix it ASAP will save you time and money in the long run. Our team at Mains Plumbers can help you find the cause of the issue and fix it for good. As a trusted plumbing services provider, our team has helped commercial and residential property owners in Dunedin for years. Aside from commercial and residential plumbing services, we also offer gas fitting services, drainlaying services for industrial and commercial properties, and emergency plumbing services. Call us today so we can check your property for plumbing issues.