If your water heater has been making popping noises, heating inconsistently, or running less efficiently, it may be time to flush it. Sediment naturally builds up inside your water heater over time, especially in areas with hard water. This buildup forces your system to work harder, wastes energy, and can shorten the unit’s lifespan.
Flushing your water heater once a year is usually enough for most homes, but homes with especially hard water or heavy usage may need flushing more often. While this guide walks you through the process, it’s also important to know when the job becomes too complex. If anything feels unsafe or you run into unexpected issues, calling a licensed water heater plumber is a smart way to protect your home and your system from damage.
Why Flushing a Water Heater Matters
Over time, minerals like calcium and magnesium settle at the bottom of the tank. As that sediment collects, several problems can occur:
- The burner or heating element has to work harder
- Water takes longer to heat
- Noise increases as sediment “pops” or boils
- Energy bills rise
- The tank becomes more prone to corrosion
A regular flush helps remove this buildup, improves efficiency, and reduces stress on the tank. It’s one of the easiest maintenance tasks you can perform to extend your system’s life.
Before You Start: Safety First
Water heaters deal with scalding water, electricity, and gas, so safety should always come first.
Here are a few precautions to take:
1. Turn off the power source
For electric heaters, switch off the breaker. For gas heaters, turn the gas control knob to “Pilot.”
2. Allow the water inside the tank to cool
Wait at least one to two hours to prevent burns.
3. Know where the shut-off valves are
You may need to stop the water flow quickly if something unexpected happens.
If any of these steps make you uncomfortable, don’t push forward. A professional plumber can handle the entire process safely and quickly.
Step-by-Step: How to Flush a Hot Water Heater
Here’s how to flush a hot water heater in 7 simple steps:
1. Turn Off the Water Supply
Find the cold-water shut-off valve at the top of the water heater and turn it to the off position. This stops additional water from entering the tank during the flush.
2. Connect a Garden Hose to the Drain Valve
Attach a standard garden hose to the drain valve located near the bottom of the tank. Run the other end of the hose outdoors or into a floor drain. Make sure the hose is positioned securely, as the water may be hot and flow quickly.
3. Open a Hot Water Faucet
Choose a sink or tub faucet and open the hot water side. This step helps release pressure in the system and allows the tank to drain more smoothly.
4. Open the Drain Valve
Carefully open the drain valve to begin emptying the tank. Water will start flowing through the hose. If the water comes out slowly or contains a lot of sediment, don’t worry — that’s exactly what the flush is meant to remove.
5. Turn the Cold Water Back On (Briefly)
Once the tank is nearly empty, turn the cold water valve back on for a few seconds. This surge of water helps stir up remaining sediment at the bottom of the tank and flush it out through the hose. Repeat this step until the draining water runs clear.
6. Close the Drain Valve and Refill the Tank
When you’re satisfied that the tank is clean, close the drain valve tightly and remove the hose. Turn the cold-water supply back on and allow the tank to refill completely. Leave the hot water faucet open until water flows steadily again — this removes extra air from the system.
7. Restore Power or Relight the Pilot
Once the tank is full, turn the breaker back on for electric units or adjust your gas control from “Pilot” to “On.” Your water heater will start reheating the tank.
When You Should Call a Professional Instead
While many homeowners can perform a basic flush, some situations call for expert help. If you notice any of the following, it’s best to contact a water heater plumber:
- The drain valve is clogged or won’t open
- Sediment is so thick that water barely drains
- You have a tankless water heater (which requires a different, more advanced procedure)
- Water leaks around the tank or nearby plumbing
- The flush doesn’t improve performance
A professional plumber has the tools and training to clean the system thoroughly, replace worn parts, and spot early signs of failure. In some cases, attempting the job yourself could make the issue worse — especially if sediment has hardened at the bottom of the tank.
If your water heater is older, inconsistent, or difficult to service, calling an expert can save you time, money, and headaches. You don’t need to feel like you have to take on everything alone.
Keep Your Water Heater Running Strong
Knowing how to flush a hot water heater is a simple but important part of maintaining your home. Regular flushing helps your system run more efficiently, reduces noise, and prevents premature failure. Still, not every situation is DIY-friendly—and there’s no shame in calling a plumber when the process gets tricky.
If you’d rather have a professional handle your water heater maintenance, repair, or inspection, Efficient Air Service is here to help.
Call us today at 973-363-9180 to schedule your water heater service and keep your home’s hot water system in top shape!
