What should I do if water smells of sulphur, rotten eggs, or sewage?

Check if it's only the hot tap — if so, your hot water cylinder temperature may be too low. Raise it to 60°C to kill bacteria. Run unused taps for 2-3 minutes to flush stagnant water. Clean your tap aerators (the mesh at the end of the spout) — bacteria can grow there.

Why Does My Water Smell Like Rotten Eggs?

By TapWater.uk Research·Updated May 2026·Independent research

Symptom

Water smells of sulphur, rotten eggs, or sewage

What causes this?

Hydrogen sulphide from bacteria growing in your hot water cylinder (set below 60°C).
Old or unused pipes where stagnant water allows bacteria to grow.
Rarely, contamination from a nearby source.

Is it dangerous?

The smell is usually harmless but unpleasant. If it's only from the hot tap, it's almost certainly bacteria in your water heater. If from both taps, contact your supplier.

What to do

1.Check if it's only the hot tap — if so, your hot water cylinder temperature may be too low. Raise it to 60°C to kill bacteria.
2.Run unused taps for 2-3 minutes to flush stagnant water.
3.Clean your tap aerators (the mesh at the end of the spout) — bacteria can grow there.

When to contact your water supplier

Immediately if the smell comes from the cold tap, or if multiple taps are affected.

Check what's in your water

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