Water & tank care
Why does my water smell like rotten eggs?
That unmistakable rotten-egg smell is hydrogen sulphide gas. It’s more unpleasant than dangerous at the levels most homes see, but it rarely goes away on its own. The first clue is whether it’s on the hot, the cold, or both.
Hot only, cold only, or both?
This narrows it fast. A rotten-egg smell on the HOT water only usually points to a reaction inside the hot water system (often the sacrificial anode reacting with bacteria in the tank). On the COLD as well, or on both, it more likely comes from the water source itself, common in bore water and some tank water, or from bacteria in the pipes or tank.
If it’s the hot water only
The hot water system is the usual source. A plumber can flush it and, on some systems, swap the sacrificial anode for a different type that doesn’t feed the reaction. It’s a known, fixable issue.
If the cold smells too
The sulphur is in your supply. In bore water it’s often naturally occurring; in a tank it can be bacteria or decaying organic matter, so check whether anything has got into the tank. Treatment options include aeration, oxidising filtration, or chlorination, matched to how strong the smell is.
What to do
- Work out hot-only versus both, it decides everything.
- For hot-only, get the hot water system looked at.
- For cold or all-water, consider a water test and a treatment matched to the cause.
- Check your tank for anything that shouldn’t be in there.
Common questions
Is rotten-egg-smelling water dangerous?
At the levels most homes get, the smell is the main problem, not a health risk. But strong or persistent sulphur, especially on drinking water, is worth testing and treating, and it can corrode fittings over time.
It only smells when I first turn on the hot tap, why?
That points squarely at the hot water system, the gas builds up in the tank and clears once fresh water flows through. A plumber can sort the tank; it’s a common fix.