On Mon, 09 Jun 2008 15:39:16 -0500, Suzie-Q
wrote:

I'm doing laundry, washing a load with hot water. I just
noticed that, while the water is running to fill the washer,
there are noises coming from the water heater. It sounds a
little like when you throw your tennis shoes in the dryer:
that bumping sound they make.

Is this a bad noise? Can anyone tell me what's causing it?

The water heater is about eight years old. I have very hard
water and have never "drained" the water heater.

Mine has made noises like that for years. It doesn't seem to hurt
anything, except maybe efficiency.