Over time, sediment and mineral buildup inside your water heater can reduce its efficiency, increase your energy bills, and even shorten the lifespan of the unit.
That’s especially true here in the Comox Valley, where local water can contain natural minerals that settle at the bottom of your tank. The good news? With a few basic tools and a bit of time, you can flush your water heater yourself and help keep it running like new.
Here’s a step-by-step guide to help you safely and effectively flush your water heater.
Why Flushing Your Water Heater Matters
Sediment buildup acts like an insulating layer at the bottom of the tank, forcing your heater to work harder to heat the same amount of water. This means:
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Higher energy bills
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Inconsistent water temperature
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Noisy operation (popping or rumbling sounds)
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Shorter lifespan for your heater
Flushing once a year can help prevent these issues—especially in areas with hard or mineral-rich water like much of Vancouver Island.
What You’ll Need
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A garden hose
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A flathead screwdriver (if needed for your drain valve)
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A pair of work gloves
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A bucket (optional, for draining in smaller batches)
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Patience and about 1–2 hours
Step-by-Step Instructions
1. Turn Off the Power or Gas
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Electric Water Heater: Locate the breaker in your electrical panel and switch it off.
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Gas Water Heater: Turn the gas valve to the “pilot” setting or shut off the gas supply entirely.
Safety Tip: Never flush your water heater while it’s still on—it can be dangerous and damage the unit.
2. Turn Off the Cold Water Supply
Find the cold water inlet valve at the top of the tank and turn it clockwise to shut it off. This prevents new water from entering while you’re flushing.
3. Let the Water Cool
If your water heater has been running recently, let it cool for at least an hour to avoid burns from hot water.
4. Attach a Hose to the Drain Valve
Connect your garden hose to the drain valve at the bottom of the tank. Run the other end to a safe drainage area, like a floor drain, bathtub, or outside.
Pro Tip: Make sure the hose is secured and positioned lower than the tank to ensure proper drainage.
5. Open the Drain Valve
Using a screwdriver or your hand (depending on the valve type), slowly open the drain valve. Hot water and sediment will begin to flow out.
6. Open a Hot Water Tap
To prevent a vacuum from forming, go to the nearest sink or tub and turn on the hot water tap. This helps the tank drain more smoothly.
7. Flush with Cold Water
Once the tank is empty, turn the cold water supply back on for a few minutes. This helps stir up and rinse out any remaining sediment. Let the water run until it flows clear from the hose.
8. Close Everything Up
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Close the drain valve and remove the hose.
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Turn off the tap you opened earlier.
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Turn the cold water supply back on fully.
9. Restore Power or Gas
Once the tank is full again (you’ll know because water will start coming out of the open hot water tap), you can restore power or relight the pilot on a gas unit.
When to Call a Professional
If you notice rust-colored water, low water pressure, or the drain valve won’t open, it might be time to call in a pro. Water heater maintenance is important, but sometimes a trained eye can spot issues before they turn into costly repairs.
Whether you’re unsure about flushing your tank or think your water heater might need a repair or replacement, Doug the Plumber is here to help. We proudly serve homeowners throughout the Comox Valley with friendly, expert plumbing service you can count on.
Call us Today!
Doug the Plumber
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