How to Flush a Water Heater

In areas with hard water, like Las Vegas Valley, Reno, and Clark County in Nevada, the water contains higher levels of calcium and magnesium. When hard water is heated in your water heater, the heating process causes these minerals to crystallize and settle out of the water, forming sediment, which accumulates at the bottom of the heater tank. Over time, this build-up becomes quite problematic, resulting in unexpectedly higher water bills, efficiency losses, and damage. To prevent these issues, call a plumbing service to flush your water heater unit at least once a year.

How to Flush a Hot Water Heater?

Tank Water Heaters

If you have a tank system, sediment has to be removed from the large reservoir that stores and heats water continuously. You need to drain the water heater first through the drain valve and then use additional water flow to help dislodge any stubborn sediment.

• Turn Off Power: For electric heaters, turn off the power at the circuit breaker. For gas heaters, set the thermostat to the “pilot” position to ensure the burner does not fire during the process.
• Connect a Hose: Attach a garden hose to the drain valve located at the bottom of the tank. Use plumber’s tape on the drain valve threads before attaching the hose to prevent leaks.
• Turn Off Water Supply: Close the cold-water supply valve to stop more water from entering the tank. This prepares the system for draining.
• Check the Temperature and Pressure Relief Valve (T&P Valve): Lift the lever on the valve and let it snap back. It should release a burst of water into the overflow drain pipe. If it does not, it needs to be replaced.
• Open the Drain Valve: To drain the water heater, start draining the water into a bucket to check for sediment chunks initially. Once you see what is coming out, you can switch to draining directly outdoors or into a drain.
• Flush With Cold Water: After the tank is largely drained (or completely empty), keep the drain valve open and turn the cold water supply back on. This will allow fresh water to flow through the tank, and help dislodge and remove remaining sediment.
• Monitor the Drainage: Keep an eye on the water flowing out through the hose. It should eventually run clear. If the water remains murky or you see a lot of sediment continuing to flow out, additional flushing might be necessary.
• Close the Drain Valve: Once the water runs clear, shut the drain valve and remove the hose.
• Refill the Tank: Turn the water supply back on to refill the tank. Open a hot water faucet somewhere in the house to bleed air from the system. Let it run until water flows without air bubbles and sputtering.
• Turn the Heater Back On: For electric heaters, restore power at the circuit breaker. For gas heaters, adjust the thermostat back from “pilot” to the normal setting.
• Monitor for Leaks: Check around the water heater, including at the drain valve and T&P valve, to confirm there are no leaks. Talk to a plumbing expert to know how often to flush the water heater.

Tankless Water Heaters

Also known as on-demand water heaters, these models do not store water. Instead, they heat it up directly via a heat exchanger as it passes through the unit. In this case, you need to remove the scale buildup from hard water minerals that might be coating and clogging the exchanger.  

• Turn Off Power: Power to the unit should be completely shut off. Gather all necessary supplies, including several gallons of white vinegar, a submersible pump, hoses, and buckets if needed.
• Close Water Valves: Make sure to locate the service ports for the inlet and outlet water connections. These are specifically designed for maintenance tasks like this and should be clearly marked. Close both the valves connected to the unit.
• Attach Hoses: Connect one hose to the inlet, and another to the outlet. These will be used to circulate a vinegar solution through the heater.
• Add Vinegar: Use household white vinegar (with about 5% acetic acid), but you may have to use a stronger “cleaning vinegar” solution (6% to 8% acetic acid concentration) for more severe scale build-up. Check the manufacturer’s recommendations to be sure. Remember, too strong a solution might harm internal components, while too weak may not be effective.
• Circulate the Vinegar: Let the vinegar circulate through the system using a submersible pump for about 45 minutes to dissolve scale and mineral build-up. Occasionally check to make sure the system is running smoothly and the vinegar is moving properly through the heat exchanger.
• Flush: After descaling, thoroughly flush the system with clean cold water at a high pressure to completely remove all traces of vinegar and loosened scale. You will want to continue flushing until the water runs clear and has no debris or vinegar smell.
• Close the Drain Valves: Once you have flushed for at least 5-10 minutes after the water appears clear, close the service valves for the flushing ports. These are where you attached the hoses for circulating the vinegar and flushing the water.
• Reconnect Water Supply: Ensure that the inlet and outlet service valves on the water heater (those used for normal operation, not the maintenance ports) are fully open so the water can flow back into the unit.
• Open Hot Water Taps: Open one or more hot water taps in your home to purge any air that may have entered the lines during the maintenance process. It is important to let the water run until it flows smoothly without any air bubbles or sputtering.

Choose Reliable 24/7 Water Heater Repair in Nevada

Does your shower not get as hot as it used to, or the hot water does not last as long? Or perhaps you unexpectedly run out of hot water on days with high usage. Contact Active Plumbing & Air Conditioning for a water heater flush service.

Every appliance needs to be cleaned every once in a while, including your water heater. Not flushing it at least once a year could make it a thriving environment for harmful bacteria. Call us at (702) 553-1171 or contact us online to book a water heater maintenance call. Our team can also teach you how often to flush your water heater.