Exactly what are the humming or rumbling sounds originating from my hot water heater?
Sometimes after a water heater has been on a while you may hear sounds coming from it like humming or rumbling. This happens because there are mineral deposits which have accumulated inside the water heater at the base and the water becomes trapped and then actually starts to boil.
This could be remedied from time to time by draining the water heater into a bathtub or floor drain. Let the water drain through the water heater for five minutes or so. This will help get rid of the sediment. Newer models are designed to prevent this mineral sediment accumulation.
WARNING: Hot water is dangerous. Don’t allow the hot water to go onto your flowers or lawn as it can kill them. Instead allow it drain into a floor drain or a laundry tub or bath tub. Remember to turn the power off on your electric heater to keep it from burning up.