As the weather warms up, it’s not uncommon for unpleasant smells to start creeping up from your drains. If you’ve noticed a bit of a whiff in the kitchen or outside near your drains lately, you’re not alone.
The good news. It’s usually something that can be sorted fairly quickly once you know what’s causing it. Here at TWC Draincare our engineers are called out every day to deal with mysterious smells. So, let’s take a look at why it happens and what you can do about it.
Why Do Drains Smell More in Summer?
Simply put, heat speeds things up. Warmer temperatures cause:
- Waste to break down faster
- Bacteria to become more active
- Odours to become stronger and more noticeable
So, a drain that’s been “just about coping” through winter can suddenly start making its presence known as soon as the temperature rises.
TL;DR
Warm weather makes drain smells worse because heat speeds up bacteria growth and waste breakdown. The most common causes are grease and food build-up, partial blockages, dry traps (unused drains), poor pipe angles, or septic tank issues.
Quick fixes:
- Run water through unused drains
- Flush drains with hot water and washing-up liquid
- Check for outside blockages
- Empty septic tanks if needed
If smells keep coming back, it usually means there’s a deeper issue that may need professional jet cleaning, CCTV inspection, or drain maintenance before it turns into a blockage or flooding problem.
The Most Common Causes of Smelly Drains
1 – Grease and Food Build-Up (Kitchen Drains)
This is one we see all the time, no matter how careful you are with your drains grease and fat can build-up in a drain line. Over months (or years), things like cooking oils, fat and food waste build up inside your pipes. When the weather warms up, these deposits soften and start releasing odours.
This is where a professional clean makes a big difference. At TWC Draincare, we use high-pressure water jetting for both our residential and commercial customers to clear out the build-up, not just push it further down the pipe. Our engineers also inspect their work with a CCTV camera to make sure its complete before they leave. They want to know the unpleasant smell is gone for good.
2 – Slow or Partially Blocked Drains
If your drain is:
- taking longer to empty
- making gurgling noises
- occasionally smelling
..it’s often a sign of a developing blockage. Left alone, these usually get worse, with a partial blockage becoming a full-blown nightmare. Don’t let that bad smell turn into a blocked toilet, or a flooded garden just when you’re trying to enjoy the sunshine.
We can quickly identify the issue and clear it before it turns into a full blockage (and a much bigger job).
3 – Dry Traps (Especially in Unused Drains)
This is a really common (and often overlooked) cause of bad smells.
Every drain in your property has something called a trap, usually a U-shaped bend in the pipe (often called a U-bend). Its job is simple but very important. It holds a small amount of water, which acts as a barrier to stop sewer gases coming back up into your home.
When everything is working properly, you’ll never notice it. But when a trap is dry, you’ll soon notice the smells it’s been holding back.
So, what causes a trap to dry out?
There are a few common reasons:
- Lack of use
If a sink, shower, or drain isn’t used regularly (for example in a spare bathroom or utility room), the water in the trap can slowly evaporate, especially in warmer weather. - Warm temperatures
Heat speeds up evaporation, which is why this issue tends to show up more in spring and summer. - Air movement in pipework
In some cases, poor ventilation or pressure changes in the drainage system can pull water out of the trap (this is known as siphonage). - Leaks or faults
Small leaks or cracks in pipework can also allow the trap to empty over time.
What can you do?
The simplest fix is often:
- Run water into the drain for 10–20 seconds to refill the trap
But if the smell comes back quickly, it could point to:
- a ventilation issue
- a developing fault in the system
- or a deeper drainage problem
If that’s the case, it’s worth getting it checked properly. At TWC Draincare, we can inspect your system and make sure everything is sealed, flowing, and working as it should, so those smells do not keep returning.
4 – Poor Drainage Falls (Incorrect Pipe Angle)
This is a less obvious issue, but one we come across quite regularly.
Drainpipes are designed to sit at a specific angle (or “fall”) so that waste flows away properly. If the angle is too shallow, or in some cases too steep, waste doesn’t move through the pipe as it should.
Instead, solid waste will settle in the pipe and build up over time. This creates the perfect environment for bad smells, as well as repeated blockages.
In warmer weather, those trapped deposits start to break down more quickly which is why smells often become much more noticeable.
What causes this?
- Ground movement over time
- Poor installation
- Older pipework starting to drop or shift
- Previous repairs that haven’t quite got the levels right
Why maintenance matters
The tricky part is that this kind of issue often develops slowly, so you might not notice it straight away. That’s why routine maintenance is so important. At TWC Draincare, we can:
- Carry out CCTV drain surveys to check pipe levels and flow
- Use high-pressure jetting to clear built-up waste
- Spot early signs of structural issues before they get worse
Catching it early can save a lot of hassle and prevent ongoing smell problems that just keep coming back.
5 – Septic Tank or Treatment Plant Issues
If your property isn’t connected to mains drainage, smells can sometimes point to:
- a tank that needs emptying
- a system that’s overdue a service
- a fault within the system
- an imbalance of bacteria in the tank
At TWC Draincare, we can inspect, service, and maintain septic tanks and treatment plants, helping you stay compliant and avoid bigger problems.
What Can You Do About It?
Try This First:
- Check the levels of your tank to see if it needs emptying
- Run water in unused sinks or drains
- Flush through with hot water and washing-up liquid
- Check outside gullies for obvious blockages
If the Smell Keeps Coming Back…
That’s usually a sign there’s something more going on. This is where we come in.
At TWC Draincare, we can:
- Clear blockages quickly and safely
- Carry out CCTV drain surveys to see exactly what’s happening
- Jet clean pipes to remove built-up waste
- Check your system is working as it should through regular servicing
No guesswork — just a proper fix.
Need Help with Smelly Drains?
If your drains aren’t smelling quite right, it’s always best to deal with it early before it turns into a bigger (and more expensive) issue.
At TWC Draincare, we’re here to help with residential and commercial:
Get in touch today and we’ll get things sorted quickly so your drains go back to doing what they should, quietly and without the smell! Call us on 👉 03333 052 243. We’d be delighted to assist.
