Why You Should Flush Your Tank Water Heater (And How to Do It)

If you live in Minneapolis or the surrounding suburbs, your water heater works harder than you might think. Our hard water causes minerals to build up inside your tank over time. If you don’t flush the system once a year, that buildup can lead to poor performance, strange noises, higher energy bills, and even early failure.

If you live in Minneapolis or the surrounding suburbs, your water heater works harder than you might think. Our hard water causes minerals to build up inside your tank over time. If you don’t flush the system once a year, that buildup can lead to poor performance, strange noises, higher energy bills, and even early failure.

In this post, we’ll explain:

• Why flushing matters

• When you should do it

• How to flush your tank water heater

• When it’s better to call a plumber

What Is a Tank Water Heater?

A tank water heater is the most common type found in homes across Minnesota. It stores and heats 30–50 gallons of water at a time. When you turn on the hot water tap, the tank releases heated water and refills with cold water to heat again.

Over time, minerals in the water (like calcium and magnesium) sink to the bottom of the tank. This buildup is called sediment.

Why Flushing Your Tank Matters

When sediment builds up in your tank, it creates several problems:

• Reduces heating efficiency The burner has to heat through a layer of scale, which takes longer and uses more gas or electricity.

• Shortens equipment life The bottom of the tank can overheat and weaken, leading to leaks or failure.

• Causes noise You may hear banging, rumbling, or popping sounds as bubbles push through the sediment.

• Limits hot water Less space in the tank means less hot water available for your family.

How Often Should You Flush It?

Most homes in the Minneapolis–St. Paul area should flush their tank water heater once per year. If you have especially hard water (which is common in the suburbs west of the city), twice a year may be better.

What You’ll Need

• A garden hose long enough to reach a drain or outside

• A flat-head screwdriver (some drain valves require it)

• A bucket and towels for cleanup

• Access to a floor drain or safe area to drain the water

Step-by-Step Guide to Flushing Your Tank Water Heater

Important: Only flush your water heater when the tank is cool, or allow several hours after use.

1. Turn Off Power or Gas

If your water heater is electric, turn off the power at the breaker. If it’s gas, set the gas valve to “off”.

2. Turn Off the Cold Water Supply

Find the cold-water valve above the tank and shut it off. This stops new water from entering during the flush.

3. Open a Hot Water Tap

Turn on a hot water faucet in your home to relieve pressure in the system.

4. Attach the Garden Hose

Connect the hose to the drain valve at the bottom of the tank. Run the hose to a floor drain, utility sink, or outside.

5. Open the Drain Valve

Use a screwdriver (if needed) to slowly open the drain valve. Hot water will begin flowing through the hose.

Let it drain for 15–30 minutes until the water slows down. Watch the water—if it’s rusty, cloudy, or full of grit, that’s sediment leaving the tank.

6. Briefly Open the Cold Water Valve

Once the tank is nearly empty, briefly turn on the cold water. This stirs up remaining sediment. Let it flush out until the water runs clear.

7. Close the Drain Valve and Refill the Tank

Shut the drain valve tightly. Turn the cold water back on. Once water flows steadily from the hot tap (you’ll hear air sputtering at first), shut the faucet off.

8. Restore Power or Gas

Turn the breaker back on (for electric) or set the gas valve to “on.” Relight the pilot if needed, or follow your manufacturer’s instructions.

What to Watch For

• If no water drains at all, the drain valve may be clogged with heavy sediment — that’s a job for a plumber.

• If the water comes out brown or full of grit, you waited too long between flushes — make it an annual habit going forward.

• If the drain valve leaks after closing it, it may need to be replaced. Some older plastic valves fail over time.