Sediment problems are unavoidable with storage-tank water heaters. At high temperatures, minerals naturally present in water form into sediment and slowly settle at the bottom of the tank. If you’re not flushing the tank annually, this sediment buildup can block the electric element or gas burner and decrease your water heater’s energy efficiency. Over time, a severe accumulation can reduce the unit’s capacity, clog the drain valve, block your home’s plumbing lines and even cause a premature water heater failure.