The Buildup In Your Water Heater Is Gross—How To Flush It

Most of us don't think about our water heater until the shower goes cold, as it sits in a dark corner of the basement or a closet, steadily working away. While it seems like a permanent fixture, it still requires a bit of hands-on attention to stay in peak condition. For example, there's some nasty buildup that needs the occasional flushing. Taking the time to understand what's happening inside that steel tank will help you maintain a more efficient and comfortable home for years to come, so let's dive into it.

What's Built Up?

Close-up of a person holding a washing machine heater element with heavy  limescale buildup, illustrating repair, cleaning, and maintenance of 
household appliances
Photo Credit: Envato Elements / kazakova0684
Photo Credit: Envato Elements / kazakova0684

As water travels through your pipes, it carries dissolved minerals like calcium and magnesium with it. When this water is heated, those minerals crystallize and settle at the bottom of the tank. Over time, these small particles join together to form a thick, sandy layer of sediment. In areas with hard water, this process happens much faster. What starts as a few grains eventually becomes a heavy crust that coats the floor of your water heater.

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The Damage Done

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Photo Credit: Envato Elements / towfiqu_barbhuyia
Photo Credit: Envato Elements / towfiqu_barbhuyia
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This buildup is bad for a few reasons. It creates a murky environment where bacteria can potentially thrive, sometimes leading to a sulfurous or rotten egg smell in your hot water. Sediment also acts as an insulator. It tends to sit right on top of the burner or heating element, forcing the unit to work much harder to heat the water. That extra stress often causes the metal tank to overheat, crack, and eventually leak.

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Cutting Off The Power

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Photo Credit: Envato Elements / LightFieldStudios
Photo Credit: Envato Elements / LightFieldStudios
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So, if you've identified an issue and decide your tank needs flushed, how do you do it? Safety is the first step before you touch any valves. If you have a gas heater, turn the thermostat to the pilot setting. For electric models, you must head to the breaker box and flip the switch to off. Heating elements in electric tanks will burn out in seconds if they aren't submerged in water, so they need to be shut off completely. Let the water inside sit for a while so you don't get burned.

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Connecting The Hose

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Close-up view of water heater pipes and valves in a utility room,  featuring colorful connectors and tubes. Essential components for 
heating system maintenance and operation. Gas boiler taps.
Photo Credit: Envato Elements / Annu1tochka
Photo Credit: Envato Elements / Annu1tochka
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Grab a standard garden hose and attach it to the drain valve near the bottom of the tank. Lead the other end to a floor drain, out to the driveway, or wherever else you want the water to go. Make sure the hose is tightened properly so it doesn't leak on your floor. You'll want to open a hot water faucet somewhere else in the house, like a kitchen sink, to let air into the system. This prevents a vacuum from forming and allows the water to flow out faster.

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Flushing It Out

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Photo Credit: Envato Elements / EdVal
Photo Credit: Envato Elements / EdVal
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Open the drain valve slowly. At first, the water might look clear, but soon you'll likely see white flakes or cloudy water rushing through the hose, that's the sediment in question. Keep the water running until it looks perfectly clear again. If the flow is oddly slow, the sediment might be blocking the valve. You can try opening the cold water inlet for a few seconds to stir things up and push the debris out of the way.

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Refilling The System

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Photo Credit: Envato Elements / Rawpixel
Photo Credit: Envato Elements / Rawpixel
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Once the water runs clear, close the drain valve, disconnect your hose, then turn the cold water supply back on to fill the tank. Keep that kitchen faucet open until water flows steadily without any air sputtering out. This ensures the tank's completely full before you restore power. If you turn the heat back on too early, you risk damaging the unit. Once it's full, flip the breaker or turn the gas knob back to your desired temperature.

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Congratulations! You've successfully tackled a chore that many homeowners ignore until it's too late. Your water heater is now running efficiently, and you've likely cleared out years of mineral buildup. You can go back to enjoying your morning routine without worrying about rising energy costs or gross, cloudy water. Now, go ahead and enjoy a hot shower knowing your heater is in top shape.