How to Descale a Tank Water Heater

Sediment is the silent killer of efficiency in your home's plumbing. Over time, minerals found in your water supply settle at the bottom of your water heater tank, creating a layer of crust that insulates the water from the heating element or burner. This forces your unit to work significantly harder, spikes your energy bills, and accelerates corrosion of the tank lining. Performing a proper descaling procedure ensures your heater lasts its full expected lifespan. Done well, you will see a return to consistent hot water temperatures and a quieter unit. This process involves isolating the power, flushing the mineral buildup, and circulating a safe cleaning agent to dissolve what the flush leaves behind.

  1. Lock Out the Power First. Turn off the power to the water heater at the circuit breaker if you have an electric unit. For gas units, turn the gas control valve to the pilot setting to prevent the burners from firing while the tank is empty.
  2. Empty the Tank Completely. Attach a garden hose to the drain valve at the bottom of the tank and run it to a floor drain or exterior driveway. Open the pressure relief valve at the top of the tank, then open the drain valve to allow the water to empty completely.
  3. Pour in the Vinegar. Once the tank is empty, close the drain valve. Use a transfer pump to feed 2–3 gallons of white distilled vinegar into the tank through the hot water outlet or the pressure relief valve port.
  4. Let the Acid Work. Let the vinegar sit inside the tank for at least one hour. This timeframe allows the acidic solution to break down the hardened calcium deposits on the tank floor and heating elements.
  5. Clear All Vinegar Out. Open the cold water supply valve to the heater to push fresh water through the system. Allow the water to run through the drain hose until the outflow runs clear and all vinegar smell is eliminated.
  6. Power Back On. Close the drain valve, disconnect the hose, and ensure the pressure relief valve is reset. Turn the water supply back on, bleed all air from your household faucets, and then flip the power breaker or turn the gas valve back to the 'on' position.