How to Drain a Water Heater

Published: February 28, 2024

Draining your water heater is an essential maintenance task that removes sediment buildup, improves efficiency, and extends the life of your unit. Whether you're performing routine maintenance, troubleshooting problems, or preparing for replacement, knowing how to properly drain your water heater is a valuable skill for homeowners.

When to Drain Your Water Heater

Draining is necessary in several situations:

• Routine maintenance: Annual flushing to remove sediment
• Noise issues: Draining to address water heater noises
• Discolored water: Removing sediment causing brown or cloudy water
• Performance problems: Improving hot water recovery
• Before replacement: Emptying the tank for removal
• Before leak repairs: Emptying to access components

Draining vs Flushing

While often used interchangeably, there's a difference:

• Flushing: Draining some water while the tank is full for quick sediment removal. See our guide on how to flush a water heater.
• Draining: Completely emptying the tank for maintenance, repairs, or replacement.

This guide covers complete draining of the water heater tank.

Tools and Materials Needed

Before starting, gather these supplies:

• Garden hose (long enough to reach a drain or outdoors)
• Bucket (for initial draining into)
• Adjustable wrench or channel-lock pliers
• Towels for spills
• Protective gloves
• Flathead screwdriver (for some drain valves)

Safety Precautions

Water heaters involve scalding hot water, electricity, and/or gas. Follow these safety measures:

• Turn off power before starting: Electric water heaters need the breaker off; gas units need the control set to "off" or "pilot"
• Allow water to cool: Wait at least 2-3 hours after turning off power before draining
• Wear protective gloves: Water may still be hot enough to burn
• Watch for pressure: Open a hot faucet to relieve pressure
• Never drain a pressurized tank: Always open a hot water faucet somewhere in the house

Step-by-Step Guide: Draining Your Water Heater

Step 1: Turn Off the Power Source

For Electric Water Heaters:

Locate your circuit breaker panel and turn off the breaker for the water heater. It should be a dedicated double-pole breaker, usually 30 or 40 amps. Verify the power is off by checking that no status lights or displays are active on the unit.

For Gas Water Heaters:

Find the gas control valve on the front of your water heater. Turn the dial to the "pilot" position (keeps the pilot lit but prevents the main burner from firing) or to "off" (extinguishes the pilot). For complete draining, "off" is recommended.

Step 2: Turn Off the Cold Water Supply

Locate the cold water inlet valve above your water heater. This is typically a gate valve or ball valve on the pipe that brings cold water into the tank. Turn it clockwise to close it completely. This prevents new water from entering while you drain.

Step 3: Open a Hot Water Faucet

Go to a faucet in your home and turn on the hot water. Choose a faucet closest to the water heater or a bathtub faucet (no aerator to clog). This serves two purposes:

• Prevents vacuum lock in the system
• Shows when the tank is empty (water stops flowing)

Leave this faucet open throughout the draining process.

Step 4: Connect the Drain Hose

Attach a garden hose to the drain valve at the bottom of your water heater. The drain valve is typically a plastic or brass spigot near the tank base. Tighten by hand, then give an extra quarter turn with pliers if needed for a snug fit (don't overtighten plastic valves).

Route the other end of the hose to a floor drain, utility sink, or outdoors where hot water can safely drain. Avoid draining onto plants or lawns—hot water kills vegetation.

Step 5: Open the Drain Valve

Open the drain valve slowly. If the valve has a handle, turn it counterclockwise. Some units have a screwdriver slot—turn slowly to open. Water should begin flowing through the hose.

Note: If no water flows, the valve may be clogged with sediment. Try opening the T&P valve briefly to release pressure, or the drain valve may need to be replaced.

Step 6: Allow the Tank to Drain Completely

Depending on your tank size (40-80 gallons), draining can take 30-60 minutes. You can speed draining by opening the T&P valve on top of the tank, but expect some water from this valve.

Watch for the flow to slow to a trickle and then stop. When water at the open faucet stops flowing, the tank is empty.

Step 7: Flush Remaining Sediment

With the tank emptied, briefly turn on the cold water supply for 10-15 seconds. This stirs up any remaining sediment. Let this water drain out. Repeat until the draining water runs clear.

This step is essential for removing sediment buildup that causes efficiency problems and noises.

Step 8: Close the Drain Valve

Once the tank is drained and flushed, close the drain valve tightly. Remove the garden hose and check that the valve is fully closed. Hand-tighten, then a small turn with pliers if necessary.

Step 9: Refill the Tank

Open the cold water supply valve. Leave the hot water faucet open—you'll hear air escaping as the tank fills. When water flows steadily from the faucet, close it. The tank is now full.

Important: Do NOT turn on power until the tank is completely full. Running an empty or partially filled water heater can destroy heating elements in seconds.

Step 10: Check for Leaks

Inspect the drain valve and connections for leaks. Tighten if necessary. Run hot water at a faucet briefly to check that everything flows freely.

Step 11: Restore Power

For Electric Water Heaters: Turn the circuit breaker back on. The elements will begin heating the water.

For Gas Water Heaters: If you turned the gas control to "off," you'll need to relight the pilot. Follow the instructions on your water heater. If the control was on "pilot," simply turn it to your desired temperature setting.

Step 12: Wait for Hot Water

Depending on your heater's recovery rate and temperature setting, hot water will be available in 30-60 minutes for gas units or 60-90 minutes for electric units.

Troubleshooting Drain Valve Problems

Drain Valve Won't Open

Sediment or mineral deposits can seize drain valves. Try these approaches:

• Apply gentle pressure, increasing gradually
• Use pliers for better leverage (carefully on plastic valves)
• Tap the valve stem gently to jar loose deposits
• If stuck, consider replacing the drain valve entirely

Drain Valve Leaks After Closing

If the drain valve drips after you've closed it:

• Sediment may be trapped in the valve seat
• Open and close the valve several times to flush debris
• If leaking persists, install a cap over the valve
• Replace the drain valve with a higher-quality ball valve

Clogged Drain Valve

If water won't flow from the drain valve:

• Sediment has completely blocked the valve
• Try back-flushing with a garden hose (thread onto drain valve and apply short bursts of pressure)
• If unsuccessful, the valve needs replacement

After Draining: Maintenance Opportunities

When your tank is drained, take advantage of the empty tank to perform other maintenance tasks:

Anode Rod Inspection

With the tank empty or nearly empty, this is an ideal time to check the anode rod. Remove it from the top of the tank and inspect for wear. If it's less than 1/2 inch thick or heavily pitted, replace it. This $30-50 part can add years to your water heater's life.

Heating Element Check (Electric)

Inspect heating elements for scale buildup. Heavy mineral coating reduces efficiency and may indicate a failing element.

Inspect for Corrosion

Visually check the inside of the tank through the anode rod hole. Extensive rust or corrosion may indicate the tank is nearing the end of its useful life.

When Professional Help Is Needed

While draining is a DIY-friendly task, some situations require professional assistance:

• Drain valve won't open or close properly
• Significant sediment buildup that won't drain
• Corrosion is visible in the tank
• You're uncomfortable with any step
• The unit is over 10 years old and showing problems

Learn when to call a water heater professional for these and other issues.

Special Situations

Draining for Replacement

If you're preparing to replace your water heater, there's no need to refill after draining. Leave the tank empty and disconnected for removal. Check our guide on signs your water heater needs replacement to confirm replacement is necessary.

Draining Before Extended Absence

When leaving home for extended periods in freezing climates, draining prevents freeze damage:

• Turn off power and water supply
• Drain the tank completely
• Leave the drain valve open
• Don't refill until you return

Emergency Draining

If your water heater is leaking actively, drain it immediately to prevent water damage. Follow the steps above, working quickly to minimize damage.

How Often Should You Drain Your Water Heater?

The recommended draining frequency depends on water hardness:

• Soft water: Annually is usually sufficient
• Medium hardness: Every 6 months
• Hard water: Every 3-4 months

For regular maintenance, a simple flush (draining a few gallons) is often enough. Complete draining is reserved for deeper cleaning, repairs, or replacement.

Preventing Future Sediment Buildup

Minimize sediment accumulation between drainings:

• Set temperature to 120°F (lower temperature reduces mineral precipitation)
• Install a water softener if you have hard water
• Use a whole-house sediment filter
• Consider tankless water heaters for your next unit
• Inspect the anode rod every 2-3 years

Regular draining as part of water heater maintenance extends the life of your unit and maintains efficiency. If you're experiencing ongoing issues despite draining, consult a water heater professional to evaluate your system.