Why Does My Bathroom Smell Like Rotten Eggs? (And How to Fix It)
A Man Standing In His Bathroom With A Funny Smell
If you have noticed a distinct "rotten egg" or sewage smell in your bathroom, you are not alone. This is a very common drainage issue in Milton Keynes homes, but it should never be ignored.
That foul odor is hydrogen sulfide gas escaping from your drainage system. Not only is it highly unpleasant, but breathing in sewer gas can be harmful to your health. Before you start spraying air freshener to mask the problem, here is a breakdown of what causes the smell and how you can fix it.
1. The Most Common Cause: A Dry P-Trap
Look under your bathroom sink. You will see a U-shaped or S-shaped pipe—this is called a P-trap. Its job is to hold a small amount of water at all times, which acts as a liquid barrier to stop sewer gases from floating back up into your home.
The Problem: If a sink, bath, or shower hasn't been used for a few weeks (for example, in a guest bathroom), the water inside the trap can evaporate, leaving the pipe completely open for sewer gases to rise.
The DIY Fix: This is the easiest fix of all. Simply run the tap or shower for 30 to 60 seconds to refill the P-trap with water. If the smell dissipates over the next few hours, you have solved the problem!
2. A Build-Up of Bacteria and Biofilm
Every time you shower or wash your hands, soap scum, hair, and dead skin cells wash down the drain. Over time, this debris can stick to the walls of your waste pipe just below the plughole. Bacteria begin to feed on this organic matter, releasing a foul, rotten egg smell.
The DIY Fix: Do not use harsh chemical drain unblockers, as they can damage your pipes. Instead, pour half a cup of baking soda down the drain, followed by a cup of white vinegar. Let it fizz for 15 minutes, then flush the drain with a kettle full of hot (not boiling) water.
3. Blocked Vent Pipes
Your plumbing system relies on vent pipes (often exiting through your roof or outside wall) to allow sewer gases to escape outdoors and to let air into the pipes so water flows smoothly.
The Problem: If leaves, bird nests, or debris block the vent pipe, the gases have nowhere to go but back inside your house. You will often hear a "gurgling" sound from your toilet or sink when this happens.
The Fix: Because vent pipes are usually located high up on the exterior of your property, this requires a professional drainage engineer to safely access and clear the blockage.
4. A Damaged Toilet Seal (Wax Ring)
If the smell is strongest near your toilet, the wax ring or rubber seal that connects the base of the toilet to the main soil pipe may have failed.
The Problem: A broken seal allows sewer gas to seep out from under the toilet base. You might also notice a slight water leak around the base or find that the toilet rocks slightly when you sit on it.
The Fix: The toilet will need to be unbolted and removed to fit a new seal—a job best left to an experienced plumber.
When to Call the Milton Keynes Drainage Experts
If you have tried running the water and cleaning the plugholes, but that stubborn rotten egg smell is still lingering, you likely have a hidden blockage or a cracked pipe within your drainage network.
M1 Drainage offers professional CCTV drain surveys across Milton Keynes, Newport Pagnell, and the surrounding areas. We can send a high-definition camera deep into your pipework to instantly locate hidden defects, blockages, or collapsed drains without any disruptive digging.
Don't live with sewer smells in your home. Call M1 Drainage for a fast, local response: 07754 856275
