If you’re hearing strange noises coming from the area where the hot water heater is located, you might want to sit up and take notice.
As the water heater ages, rumbling noises will begin getting louder as the tank is heating up the water that’s inside. These noises are generally caused by sediment buildup in the bottom of the tank, especially if it hasn’t been drained on a regular basis.
You could try flushing the tank first, before spending money on a replacement. But it’s best to have this done by a licensed plumber, who can also evaluate the unit and let you know how to proceed.