Washing Machine Smells Like Sewage Your Fix-It Guide
That unmistakable sewage smell coming from your washing machine is a nasty surprise. It’s usually down to one of two things: a build-up of gunk inside the machine itself, or a problem with your home's plumbing. The trick is figuring out which one it is before you start pulling things apart.
Diagnosing That Sewage Smell From Your Washer
Before you grab the cleaning supplies, a little detective work can save you a world of effort. Ask yourself: does the smell only appear when the machine is running, or is it hanging around all the time? A constant pong often points to a plumbing issue, not the appliance.
This is a more common problem than you might think. Many households dealing with a smelly washer find the root cause is actually sewer gas getting in from dodgy P-traps or blocked drain pipes. It’s easy to blame the machine when the real culprit is hiding in the wall.
A dry P-trap is a classic offender. This is the U-shaped pipe under your standpipe that holds a bit of water to block sewer gases. If you haven't used the washer in a while, that water can evaporate, breaking the seal and letting those foul odours right into your utility room. You can find out more about tackling this in our guide on how to stop smells from drains.
Quick Diagnosis Guide to Sewage Smells
To help you narrow down the source of that unpleasant aroma, we've put together a quick reference table. Think of it as a starting point for your investigation.
| Potential Cause | Common Symptoms | First Action to Take |
|---|---|---|
| Clogged Drain Filter | Smell is strongest after a cycle; water drains slowly. | Locate and clean the filter (usually on the front bottom of the machine). |
| Biofilm in the Machine | A musty, sewer-like smell coming from the drum or seal. | Run a hot maintenance wash with a specialised cleaner or white vinegar. |
| Blocked Standpipe | Gurgling sounds from the drain; smell is constant, not just during a wash. | Try a drain unblocking product or manually clear the pipe. |
| Dry P-Trap | Smell appears after a long period of not using the machine. | Run a short rinse cycle to refill the P-trap with water. |
This table should give you a good idea of where to begin. Most of these issues are straightforward to check, and identifying the cause is half the battle won.
The Hidden Grime Causing Odours
More often than not, that sewage smell you're noticing isn't actually coming from the sewer. The real culprit is usually a thriving ecosystem of mould, mildew, and bacteria that has set up camp right inside your washing machine.
This slimy build-up, known as biofilm, is a nasty cocktail of old detergent, fabric softener residue, body oils, and trapped lint. It loves to accumulate in the warm, damp corners of your appliance—like the rubber door seal, the detergent drawer, and even deep within the drum—creating the perfect breeding ground for those foul smells.
It's a surprisingly common issue. Many homeowners don't realise that regular cleaning is essential to prevent this build-up. Neglecting this maintenance is a fast track to unpleasant odours.
Tackling this hidden grime is the first step. And if you're already dealing with musty-smelling clothes, checking out some tips for eliminating mildew odors from clothes can also help you get ahead of the problem in your machine.
Your Action Plan for a Deep Clean
Right, it's time to roll up your sleeves and get that horrible smell gone for good. We're going to tackle the grime head-on, starting with the most common hiding spots for biofilm.
Your first targets are the rubber door gasket and the detergent dispenser. These areas are notorious for harbouring gunk. Pull the dispenser drawer right out and give it a thorough scrub in warm, soapy water until every last bit of residue is gone.
Next up is the drain pump filter. You’ll usually find it behind a little flap at the bottom front of your machine. Be prepared—this component traps all sorts of nasties like lint, hair, and stagnant water, making it a prime source of that sewage smell. Have a shallow tray and a towel ready to catch any water that escapes.
For a more in-depth walkthrough on getting into all the nooks and crannies, our complete guide on how to clean a washing machine has you covered.
Once you’ve cleaned the individual parts, it’s time to flush out the drum and internal pipes with a hot maintenance wash. To really blast away any lingering bacteria, a little bleach can work wonders. This guide to disinfectant solution bleach offers some excellent tips for using it safely and effectively in your machine.
Keeping Your Washing Machine Fresh
So you’ve banished that awful sewage smell. Now what? The last thing you want is for it to creep back in a few weeks. Sticking to a simple maintenance routine is your best bet for keeping things fresh. A smelly washing machine is a surprisingly common problem, but it’s one you can prevent.
In fact, a 2023 survey found that over 45% of UK households have noticed nasty whiffs coming from their machines. Interestingly, the data also highlighted that high-efficiency models were 20% more likely to have these odour issues. That’s because the cooler, low-water washes they run aren't always great at flushing away all the gunk. You can read a bit more about these findings over on RTE.ie.
So, what’s the secret to stopping the smell from returning? It's all about air and using the right amount of detergent. After every wash, leave the machine door and the detergent drawer open just a crack. This tiny change makes a massive difference, letting air circulate and dry everything out. Without that dampness, mould and mildew just can't get a foothold. And be mindful of how much detergent you’re using – piling it in is one of the main culprits behind that smelly biofilm build-up.
When You Need a Professional Plumber
You've scrubbed every part, run countless cleaning cycles, and followed all the advice, but that awful sewage smell just won't go away. It’s disheartening, and it's a sure sign that the problem is bigger than just the appliance itself.
If your washing machine smells like sewage despite a thorough deep clean, it’s time to hang up the rubber gloves. Trying to fix it further on your own probably won't help.
A smell that stubborn usually points to a deeper issue in your plumbing system. We could be talking about anything from a seriously clogged standpipe to a faulty P-trap that’s failing to stop sewer gases from creeping back up. In some cases, the blockage might be somewhere in your main household drainage system.
Ignoring these warning signs can quickly turn a smelly nuisance into a major plumbing emergency. A constant sewage smell isn’t just unpleasant; it's your home’s drainage system screaming for expert attention.
Don't risk causing serious water damage or making the problem worse. Knowing when to call in the experts is key, and if you're not sure where to start, you can learn how to find a good plumber with our handy guide.
If you've tried everything and that sewage smell just won't budge, it's a strong sign that the problem lies deeper in your plumbing. Don't risk letting a small issue escalate into a major one. Contact Go Assist today to book a visit from one of our expert plumbers and get your home smelling fresh and clean again. Book your professional plumbing repair online.
