OK, so I've read all over the net and this is NOT a typical noise, so please read the post before making suggestions.

I've recently moved into a home in Utah, we have very hard water, this water heater is 14 years old, so we've only been with it for 8 months.

The unit makes popping, rumbling sounds, but it's not ALL the time, but most of the time.

It's not when the unit is running the burner, it's when there is incoming water. It will often make these noises after the first couple seconds of running water... it will even make these sounds when running cold water... I know right?

I've drained the unit and found no sediment coming out of the hose, it ran clear from start to finish.

I'm stumped.. I did find a post that said if you have an aluminum rod and high PH, you should change to a magnesium rod. I have no idea if that's the issue or even what that means.

Hope you can help.

The inside of the tank's center flue has "nodes" on it. The water in the node gets superheated under pressure. When you open ANY faucet, hot or cold, and the pressure drops the superheated water condenses with a "mini explosion" causing the sounds you hear. THe only cure is a new water heater.

At 14 years with hard water, you're on borrowed time anyway.