Sediment buildup is the layer of calcium carbonate, magnesium, and other minerals that settles out of heated water onto the bottom of a tank water heater. The layer insulates the water from a gas burner or buries the lower electric element, causing popping or rumbling noises, slower recovery, reduced capacity, and overheating of the tank floor.
Why it matters to you
Hard water is common across much of the country, and unflushed sediment shortens tank life while making the heater spend extra energy heating minerals before it heats water.
Practical guidance
Flush the tank through its drain valve once a year: turn off the power or set the gas control to pilot, close the cold supply, attach a hose, and drain until the water runs clear. If the drain valve is clogged or the tank is old, have a pro handle the flush rather than forcing the valve.