Quick answer: A drain usually smells because a water trap (U-bend) has dried out and is letting sewer gas back up into the room, or because fat, grease, food and biofilm have built up inside the pipe. Running water to refill the trap and cleaning out the build-up clears most household smells. If the smell keeps coming back, it often points to a partial blockage further down the pipe that needs clearing. For a persistent or strong sewer smell in Brighton or Hove, call Danny on Call 07459 599505.
Why does my drain smell?
A drain smells when sewer gas or rotting waste is able to reach your nose instead of being sealed away. There are a few common causes:
- A dried-out U-bend or trap. Every sink, basin, shower and toilet has a bend that holds a small plug of water. That water seals the pipe and stops sewer gas rising up. In a sink or shower that is rarely used, the water slowly evaporates and the seal is lost, so you get a drain-like or sewage smell coming straight up the plughole.
- Fat, grease and food build-up. In kitchen drains, fat and food waste cling to the inside of the pipe, turn rancid and smell. This is one of the most common causes of a bad-smelling kitchen sink.
- Biofilm. A slimy layer of bacteria coats the inside of pipes and overflows, especially in bathroom basins. It can give off a musty or eggy smell even when water is flowing normally.
- A partial blockage further down. When waste is only half draining away, it sits and rots in the pipe. You may notice slow draining as well as the smell.
- A blocked or restricted soil vent pipe. The vent pipe lets drain gases escape safely above roof level. If it is blocked (for example by leaves or a bird's nest), gases can be forced back through the traps in the house instead.
- A dry or dirty outside gully. The gully is the small grid outside where waste water discharges. If it is choked with silt, leaves and grease, it can smell across the whole back of the house.
Sussex note: Many Brighton and Hove terraces sit on older, shared Victorian drainage. When one of these shared runs is partially blocked, the smell can appear at more than one property at once, and it tends to keep returning until the run is properly cleared.
How do I get rid of drain smells?
Start with the simple fixes, then move to clearing the pipe if the smell persists.
- Run the water. If the smell is from a rarely used sink, bath or shower, run the tap or shower for a minute to refill the trap. Pouring a jug of water down an unused plughole once a week keeps the seal topped up and the smell away.
- Clean the trap. Under most sinks the U-bend unscrews by hand or with a wrench. Put a bucket underneath, unscrew it, and clear out the trapped hair, food and gunge. This deals with the smell at its source in the trap.
- Hot water and soda for grease. For a greasy kitchen drain, pour a kettle of hot (not boiling) water down, followed by a good handful of soda crystals dissolved in hot water. This helps shift the fat coating the pipe. Repeat weekly if your kitchen drain is prone to it.
- Clear the outside gully. Lift or scrub the grid outside and scoop out the silt, leaves and grease sitting in the gully trap so waste water can flow away freely and stops standing and rotting.
- Check the vent. If smells appear indoors whenever an appliance drains, the soil vent pipe may be restricted. This one is usually best left to us to check and clear safely.
Avoid tipping strong chemical drain cleaners down repeatedly. They rarely fix the underlying build-up and can sit in a blocked pipe.
When does a smelly drain mean a blockage?
A smell means a blockage when it keeps coming back after cleaning, or comes with slow draining, gurgling or waste water rising in the gully. Those are signs that waste is sitting and rotting in a pipe that is partly or fully blocked, and no amount of topping up traps will fix it. At that point the pipe needs clearing.
We clear the blockage at the source using drain rods, high-pressure water jetting and plunging, so the waste flows away freely and the smell goes with it. Jetting is particularly effective at stripping out the fat, grease and build-up that cause recurring kitchen and bathroom smells.
If you have a persistent drain smell, book blocked drain clearance and we will get it sorted. We cover Brighton, Hove and the surrounding Sussex area, 24/7.
Smell won't shift? Get it cleared today. Call 07459 599505