If your water heater has started making loud popping or rumbling noises, you are likely hearing the sound of steam bubbles escaping through a layer of sediment on your tank’s bottom.
Over time, minerals in your water settle at the bottom of the heater. This sediment buildup forces your unit to work harder, raises your energy bills, and can eventually cause the tank to rust and leak. The solution is to flush the tank.
While many homeowners search for how to drain a water heater to fix this themselves, it is not as simple as turning a handle. You are dealing with scalding water, high-voltage electricity (or gas lines), and pressure vessels.
At Deljo Heating and Cooling, we believe in honest advice. Below is the guide on how to flush a hot water heater safely. First, though, we need to talk about when you shouldn’t do it yourself.
🛑 STOP: Read This Before You Touch the Valve
Before you grab a garden hose, check the age of your water heater.
If your water heater is 8-10 years old (or older) and has never been flushed: DO NOT OPEN THE DRAIN VALVE.
Older units often have plastic drain valves that become brittle over time. If you force an old valve open, it may snap off or refuse to close again. This turns a routine maintenance afternoon into a flooded basement and an emergency plumbing bill.
Other risks of DIY draining include:
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Severe Scalding:
Water inside the tank can be upwards of 140°F. This can cause third-degree burns in 5 seconds or less if a hose slips or leaks.
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Flooding:
Once you open that valve, you have to be sure you can close it. Sediment can get stuck in the valve, preventing it from sealing shut.
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Dry Firing:
If you turn an electric heater back on before the tank is full, you will burn out the heating element instantly.
If you are uncomfortable with these risks, or if your tank is old, please contact Deljo Heating and Cooling. We can handle the maintenance safely.
The Process: How to Drain Your Hot Water Heater Safely
If you have verified that your unit is new enough to handle a flush and you are ready to proceed, follow this exact sequence to avoid damage or injury.
1. Deactivate the Unit
Safety First: You must stop the heating process before the water level drops.
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For Electric Water Heaters:
Go to your circuit breaker panel and flip the water heater’s breaker to the OFF position. Critical Warning: If you skip this step, the heating elements will burn out the moment the water drains, requiring expensive repairs.
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For Gas Water Heaters:
Locate the thermostat dial near the bottom of the tank and rotate it to the “Pilot” or “Vacation” setting.
2. Stop the Water Flow
Find your water heater’s cold water intake pipe. Turn the shut-off valve (usually a blue handle or a wheel) clockwise until it is fully closed. This stops new water from refilling the tank while you work.
3. Attach Your Hose
Find the drain valve near the bottom of the tank. Thread a standard garden hose onto the outlet securely. Run the discharge end of the hose to a floor drain, sump pit, or directly outdoors. Keep the hose flat to prevent back-pressure, and remember: the water inside is scalding hot.
4. Create Airflow (Break the Vacuum)
Water won’t flow out if air can’t get in (think of putting your thumb over a straw). To fix this, go to a sink or tub on the highest floor of your house and turn on the hot water tap. Leave it running. This pulls air into your system’s pipes and allows the tank to drain freely.
5. Open the Valve and Drain
Using a flathead screwdriver or the valve handle, slowly open the drain valve at the bottom of the heater. Allow the water to flow until it looks clear and free of sediment particles.
Is it stuck? If the flow is weak, sediment might be clogging the valve. Briefly turn the cold water intake back on for 5–10 seconds to blast the blockage loose, then shut it off again.
6. Close Up the System
After the water begins running clear …
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- Tightly close the drain valve.
- Unscrew and remove the garden hose.
- Important: Keep that upstairs hot water tap OPEN.
7. Refill the Tank
Turn the cold water intake valve back on. You will hear the tank filling up. Go back to the open faucet upstairs. You will hear air sputtering and hissing. This is normal. Wait until a smooth, steady stream of water flows from the tap. This confirms the air is gone and the tank is 100% full.
8. Power Back On
Only after water is flowing steadily from your taps is it safe to turn the breaker back on or turn the gas dial back to “ON.”
Skip the Hassle and Call Deljo
Learning how to flush a water heater sediment can save you money. Unfortunately, it also has the potential to be a dangerous, messy hassle.
If you would rather spend your weekend relaxing instead of hauling hoses and worrying about scalding water, let the family-owned team at Deljo handle it. Our comprehensive water heater expertise means we can inspect your unit, flush the sediment, and check for safety issues in one quick visit.
Keep your basement dry and your family safe. Call us today or schedule your service online.
