A good indication that you need to replace the water heater would be if it is leaking, the ceiling is leaking, or if you do not have hot water. Water in the pan of your unit is one of the most common signs that it needs to be replaced. However, what causes the pan to fill with water is not as commonly known. A lot of people do not realize they are supposed to drain the water heater every six months according to the manufacturer’s maintenance instructions. Although, once a year should suffice. When water heaters are not drained annually, a sediment builds up inside of the tank as the unit heats and contracts. This could cause a hole in the lining or for the tank to begin to rust out.