How Often Should You Flush Your Water Heater?

If your showers run cold sooner than they used to, or you hear a low rumble coming from your water heater, sediment buildup is usually behind it. Flushing the tank clears that sediment out, and it's one of the easiest ways to get more years out of the unit.

Bell Plumbing, Heating, Cooling & Electrical has been helping homeowners look after their water heaters in Denver since 1926, and this is one of the questions we field most.

Here's a clear answer, along with what makes our local water worth paying attention to.

The Short Answer: Once a Year

For a standard tank water heater, plan on flushing it once a year. That schedule keeps mineral sediment from collecting on the bottom of the tank, where it forms a crust that separates the burner or heating element from the water it's supposed to heat. The result is a unit that works harder, costs more to run, and wears out sooner.

Denver's water gives you extra reason to stay on top of it. Our supply sits on the harder side of the scale, and it tends to get harder in the winter when reservoir levels drop and the water carries more dissolved minerals. Every time that water heats up, some of the calcium and magnesium settles out inside your tank. Homes in the southern and eastern suburbs, and anyone drawing from a private well, often see even higher mineral content, so those tanks can need attention more than once a year.

A few situations call for a more frequent flush:

• Very hard water at your address, which is common in the southern metro and on well water
• A busy household that runs through hot water every day
• An older unit already showing signs of buildup
• No water softener on the incoming line

With soft water and a light hot-water load, you can sometimes stretch the interval a little. When you're not sure, once a year is the safe default, and it fits neatly into regular water heater maintenance.

Why Sediment Causes So Much Trouble

That layer of grit at the bottom of the tank does more damage than most people expect. On a gas unit, it acts like insulation between the flame and the water, so the burner runs longer to hit the same temperature. On an electric unit, sediment can bury the lower heating element and burn it out early. Either way, you're paying to heat rock instead of water.

Buildup also eats into how much hot water you actually get, since sediment takes up space that used to hold water. The popping and rumbling you hear is steam bubbles fighting their way up through the sludge. Left alone long enough, that trapped heat can stress the tank lining and shorten the life of the whole unit.

How to Flush the Tank Yourself

If you're comfortable with basic tools, you can handle a flush in under an hour:

1. Turn off the power at the breaker for an electric model, or set a gas unit to "pilot."
2. Shut off the cold water supply valve at the top of the tank.
3. Connect a garden hose to the drain valve near the bottom and run the other end to a floor drain or outside.
4. Open a hot water tap somewhere in the house to let air in, then open the drain valve.
5. Once the tank empties, briefly turn the cold supply back on in bursts to stir up and rinse out the remaining sediment until the water runs clear.
6. Close the drain, remove the hose, let the tank refill fully, then restore power or gas.

One safety note: the water coming out is scalding, so keep hands and feet clear of the discharge. If the drain valve won't open, or the water still runs cloudy after several rinses, that's a sign the buildup has gotten ahead of you, and it's worth calling in a pro.

What About Tankless Water Heaters?

Tankless units don't store water, so they don't collect sediment the same way. They still need descaling, though, because hard water leaves scale on the heat exchanger. In an area like ours, once a year is a reasonable target, and heavier mineral loads may call for more. Keeping up with it protects the efficiency that makes a tankless water heater worth having in the first place.

Signs Your Flush Is Overdue

Watch for these:

• Rumbling, popping, or crackling from the tank
• Running out of hot water faster than usual
• Hot water that looks rusty or smells metallic
• The unit taking longer to reheat between uses
• Moisture or small puddles near the base

If a flush doesn't bring things back to normal, the unit may need a closer look. Sometimes it's a straightforward fix, and sometimes an aging tank is telling you it's near the end. Our team can walk you through water heater repair or replacement options and give you an honest read on which makes more sense.

Book Your Water Heater Flush With Bell

Staying ahead of sediment is far cheaper than replacing a tank early, and it's the kind of quick job that pays for itself. If you'd rather leave it to someone who does it every day, Bell offers same-day service across Denver, so you're not waiting around for hot water to come back. 

We've been the name metro-area homeowners have trusted for 100 years, and we'd be glad to help. Schedule an appointment and we'll take it from there.

Call (303) 731-5469