Most water heaters employ a large, insulated holding tank to ensure there's plenty of hot water on hand at all times for different purposes throughout the home. Over time, naturally occurring minerals in the water, as well as sand and grit flushed from municipal water lines, can settle in the bottom of the tank. This sediment buildup can potentially reduce the efficiency and capacity of your water heater. It can also plug the drain and interfere with ongoing maintenance, leading to early failure. Draining a water heater to remove sediments is an easy DIY that takes very little time and just a few basic tools.