Flushing your water heater removes harmful sediment that reduces efficiency and shortens its lifespan. Learn why flushing beats simple draining and how to do it yourself to save money and avoid sudden failures.
Water Heater Sediment: Causes, Signs, and How to Fix It
When water heater sediment, mineral deposits like calcium and magnesium that settle at the bottom of your water tank over time. Also known as tank scale, it’s the silent killer of water heaters—slowly eating away at efficiency, heating speed, and lifespan. If your hot water runs out faster than it used to, or you hear strange popping or rumbling noises, sediment is likely the culprit. It doesn’t just block heat transfer—it forces your heating elements to work harder, which burns them out faster and spikes your energy bill.
Water heater sediment doesn’t appear overnight. It builds up because most tap water contains dissolved minerals. When the water heats up, those minerals drop out and stick to the tank’s bottom. Over time, this layer grows thicker, like rust on a pipe. A few inches of sediment can cut your heater’s efficiency by 20% or more. You’ll notice it when your showers feel lukewarm, the reset button keeps tripping, or your water smells like rotten eggs—because sediment traps bacteria. And if you’ve got an electric water heater, that sediment can literally cover the heating element, making it overheat and fail. Gas heaters aren’t safe either—the layer insulates the burner, causing overheating and cracks in the tank.
Fixing this isn’t rocket science, but it’s often ignored until it’s too late. Flushing your tank once a year removes most of the buildup. You don’t need a pro—just a garden hose and 30 minutes. But if your heater is over 10 years old and you’ve never flushed it, you might be looking at a full replacement. A 20-year-old water heater with heavy sediment isn’t worth saving—it’s a liability. And if you’re hearing loud bangs or seeing rusty water, that’s not just sediment—it’s the tank itself breaking down. The good news? Catching it early means you avoid a cold shower and a big repair bill. Below, you’ll find real fixes from people who’ve been there: how to test for sediment, when to flush, what tools you need, and how to tell if your heater is beyond saving.