I've noticed my water at home smells a bit "earthy". It's much more pronounced when hot. I called the city- we're on public water- who tested it while cold and said it's within state limits. When I pass the water through a drinking filtration system, it smells just fine.

Could this be a bacterial bloom of some sort in my hot water tank?

  • Doubtful, but what temp is your hot water in the tank? Generally it too hot for bacteria to grow....
    – Tyson
    Jun 3, 2017 at 16:40
  • Is the odor detectable in water straight from cold lines (which do not pass through the water heater)?
    – feetwet
    Jun 3, 2017 at 18:59
  • Seems to be more from hot than cold but I can detect a bit in cold. Of course there could be mixing in the pipes. I suppose it's harder to detect when the cold water has been running a while but the odor is so faint some times I'm not 100% sure.
    – Megatron
    Jun 3, 2017 at 19:19

1 Answer 1


Smells from bacteria tend to be "foul", the kind of odor that makes your stomach queasy. Heavy concentrations of the minerals and sediment normally found in water can have an "earthy" smell, and these can collect in your hot water tank.

Your hot water tank should have a spigot near the bottom. It's there for periodically purging the minerals and sediment that collect at the bottom. Stick a basin under the spigot and open the valve. What comes out into the basin will likely contain a lot of particles that look like sand. You usually don't have to let it run for long, the sediment will wash out quickly. It's a good idea to do this periodically (maybe once a year or so).

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