Why Does My Sink Smell, and How Do You Get Rid of It?
Most smells can be cured by cleaning out the trap or simply running the tap. Here is how to work out which problem you have.
A smelly sink is usually caused by waste trapped in the U-bend or waste pipe. Food scraps, grease, hair and soap build up out of sight, and as bacteria break them down, they release that familiar drainy smell. Less often, the smell is sewer gas coming up through a sink whose trap has dried out or been emptied by poor drainage further down the system.
Most smells can be cured by cleaning out the trap or simply running the tap. However, a smell that keeps returning is often the first sign of a blockage forming. Here's how to work out which you're dealing with and what to do about it. If it does turn out to be a blockage, our sink unblocking service covers Essex, London and the M25.
What Causes a Smelly Sink?
Almost every drain smell traces back to one of these five causes.
Build-up in the trap and waste pipe
This is by far the most common cause. In a kitchen, it's food waste and cooking fat. In a bathroom, it's hair, toothpaste and soap scum. All of it clings to the inside of the U-bend and the waste pipe, where it sits in a warm, damp spot and slowly rots.
A dirty overflow
Bathroom basins have an overflow hole near the top of the bowl. Over time, the channel behind it collects grime and stale water, which can smell surprisingly strongly. It's easy to miss because you never see inside it.
A dried-out trap
Every sink has a trap that holds a small amount of water. That water forms a seal and stops smells from the drain coming back into your home. If a sink isn't used for a while, perhaps in a spare bathroom or a property that's been empty, the water can evaporate.
A trap being emptied as the sink drains
Sometimes the trap loses its water even when the sink is in regular use. If air can't move freely through the drainage system, draining water can suck the seal out of the trap with it. You'll often hear gurgling when this happens. A partial blockage further down the pipe is usually to blame.
A blockage further down the drain
If the smell is strong and seems to come from more than one plughole, the problem may be deeper in the system. Waste trapped in the main drain can send odours back up through every connected fitting.
What Does the Smell Tell You?
The type of smell can point you in the right direction. A sour, rotting food smell from a kitchen sink usually means build-up in the trap or waste pipe. A musty, damp smell from a bathroom basin often comes from the overflow or from hair and soap scum. A sewage or rotten egg smell is different. It suggests drain gases are getting into the room, usually because a trap has dried out or been emptied, or because there's a blockage further down.
How Do You Get Rid of a Smelly Sink?
Start with the simple fixes. In many cases, one of these will solve the problem completely.
Run the tap
If the sink hasn't been used for a while, run water for a minute to refill the trap and restore the seal. If the smell disappears, a dry trap was the cause.
Clean the plug and overflow
Remove the plug if you can and clear any hair or grime around it. Use a small bottle brush to clean inside the overflow channel.
Clean out the trap
Most sink traps unscrew by hand. Put a bucket underneath first, then remove the trap, empty it and rinse it out before refitting it securely.
Run hot water, not boiling
Hot tap water helps rinse away fresh grease. Avoid pouring boiling water into the sink, as it can damage plastic pipes and even crack ceramic basins.
What you should avoid is pouring chemical drain cleaners into the sink. They can damage plastic pipework and give off harmful fumes, and they rarely deal with a solid build-up. They can also make the job more dangerous if a professional later needs to take the pipework apart.
When Does a Smelly Sink Mean a Blockage?
A smell on its own isn't always a blockage. However, if the smell comes with any of the following, there's a good chance waste is building up in the pipe:
- The sink drains more slowly than it used to
- You hear gurgling as the water goes down
- The smell comes back within days of cleaning the trap
- Several sinks or plugholes smell at the same time
- Your outside drain or gully smells as well
These signs suggest the problem sits beyond the trap, where you can't safely reach it yourself. Left alone, a partial blockage like this tends to get worse until the sink stops draining altogether.
How Does A+ Drainage Services Fix a Smelly or Blocked Sink?
First, Keith works out exactly where the problem is. That might be the trap, the internal waste pipe or the drain further down. Where needed, he takes the pipework apart and removes the build-up with professional tools instead of harsh chemicals.
Once everything is cleared, the sink is flow tested and checked for leaks. Because the work happens inside your home, Keith wears shoe covers and protects your surfaces throughout. The work area is left clean and sanitised before he leaves.
There's no callout fee, and you'll get a transparent price before any work begins. That careful, honest approach has earned A+ Drainage Services more than 500 top-rated reviews across Google, Checkatrade and TrustATrader.
Frequently Asked Questions
Common questions about smelly and blocked sinks.
Why does my sink smell like drains?
A sink usually smells because food waste, grease, hair or soap has built up in the U-bend or waste pipe and is being broken down by bacteria. A sewage smell can also mean the water seal in the trap has dried out or been emptied, letting drain gases into the room.
Why does my bathroom sink smell when the drain isn't blocked?
The most common causes are grime in the overflow channel or a build-up of hair and soap scum in the trap. If the sink isn't used often, the water in the trap may also have evaporated, allowing drain smells to come up through the plughole.
How do I get rid of a smelly sink drain?
Run the tap to refill the trap, clean the plug and overflow and unscrew the trap to empty and rinse it. Avoid chemical drain cleaners and boiling water. If the smell keeps coming back, a professional can clear any build-up further down the pipe.
Does a smelly sink mean it's blocked?
Not always, but it can be an early sign. If the smell comes with slow drainage or gurgling, returns soon after cleaning or affects several plugholes, a blockage is probably forming in the waste pipe or drain.
Why does my sink smell like rotten eggs?
A rotten egg smell is usually caused by drain gases. This often happens when the water seal in the trap has dried out or been emptied, or when there's a blockage further down the drain.
Do you charge a callout fee for a smelly or blocked sink?
No. A+ Drainage Services never charges a callout fee. Keith assesses the problem and gives you a transparent price before any work begins.
Smelly Sink That Won't Go Away?
Don't put up with drain smells or a sink that's starting to slow down. A+ Drainage Services offers fast, clean sink unblocking across Essex, London and the M25, with no callout fee.