Hot Water Smells Sour?

if you have hard water some of the minerals can settle to the bottom of the tank. there is a faucet at the bottom of the tank. turn off the heater and let it cool down and hook a hose to the faucet and drain it out. you'll probably be surprised at the color of the water that first comes out. i live in an area where there is a lot of coal and the water can be almost black in the bottom of the tank. i suppose if you don't use it much or it has been turned off for a while bacteria could build up, but my guess would be minerals. good luck

I have well water and the hot water smell really bad,
my husband changed the tank and the water still smelt. a guy told us that you have to take out the anold rod, we havent done that yet but plan to soon.

I have a rotten smell from my hot water, it started to smell after buying a new hot water heater. old one never smelled had it for 15 years. had to put a rod in the new one and is smelling after one year.