Water Heater Making Noise: Causes & Fixes

Quick Symptom-to-Cause Diagnosis

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Cause 1: Sediment Buildup (Most Common)

Minerals like calcium and magnesium naturally settle at the bottom of the tank over time. When the burner or element heats water trapped beneath this sediment layer, it creates the characteristic popping or rumbling sound.

1. Turn off the cold water supply valve at the top of the water heater.
2. Attach a garden hose to the drain valve at the base of the tank and run the other end to a floor drain or outside.
3. Open a hot water faucet inside your home to allow air into the system.
4. Open the drain valve and allow the tank to flush completely. Flush until the water runs clear (this may take 10–20 minutes).
5. Close the drain valve, remove the hose, and refill the tank before restoring power or gas.
6. If flushing does not resolve the noise after 1–2 flushes, heavy scale may require a descaling treatment or tank replacement.

Recommended maintenance: Flush the tank every 6–12 months to prevent recurrence. For guidance, see the U.S. Department of Energy’s water heater maintenance guide.

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Cause 2: Restricted or Partially Closed Inlet Valve

A water supply valve that is only partially open creates a narrowed flow path, producing a high-pitched whining or screeching noise as water is forced through the restriction.

1. Locate the cold water inlet valve at the top of the water heater.
2. Check that the valve handle is fully open — a ball valve handle should be parallel to the pipe; a gate valve should be turned fully counterclockwise.
3. If the valve is fully open and noise persists, check other shutoff valves along the supply line for the same issue.
4. If a valve is damaged or does not open fully, replace it.

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Cause 3: Water Hammer (Banging / Knocking)

Water hammer occurs when fast-closing valves—like those on washing machines or dishwashers—abruptly stop water flow, sending a pressure shockwave through the pipes that produces a loud banging noise near the water heater.

1. Turn off the main water supply and open faucets throughout the house to drain residual pressure from the pipes.
2. Turn the main supply back on slowly — this can re-charge air chambers in older plumbing and reduce hammering.
3. If the problem recurs, install a water hammer arrestor on the supply line near the appliance causing the noise.
4. Check your home’s water pressure with a gauge attached to an outdoor hose bib. Pressure above 80 PSI can cause hammering; a pressure reducing valve (PRV) may be needed.

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Cause 4: Failing Heating Element (Electric Water Heaters)

On electric water heaters, a heating element coated in mineral scale or beginning to fail can produce a sizzling, crackling, or popping noise as it struggles to heat water efficiently.

1. Turn off the circuit breaker for the water heater.
2. Turn off the cold water supply and drain about one-third of the tank using the drain valve.
3. Remove the access panel(s) on the side of the tank and pull back the insulation to expose the element.
4. Use a multimeter set to resistance (Ω) to test the element — a reading of OL (open loop/infinite resistance) means the element has failed and must be replaced.
5. Unscrew the old element using an element wrench and install a new one rated to the same wattage and voltage. Apply plumber’s tape to the threads.
6. Refill the tank completely before restoring power to avoid dry-firing the new element.

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Cause 5: Pressure Relief Valve (T&P Valve) Hissing

The temperature and pressure relief (T&P) valve is a critical safety device that opens to release excess pressure. A hissing sound from this valve means it may be venting due to high pressure or temperature — or the valve itself is worn and leaking.

1. Do not ignore this noise. A continuously venting T&P valve indicates dangerous pressure levels or a faulty valve.
2. Check the thermostat setting on the water heater — it should be set to 120°F (49°C). Reduce it if set higher.
3. Check your water supply pressure at a hose bib. If above 80 PSI, have a plumber install or adjust a pressure reducing valve.
4. If pressure and temperature are normal but the valve still hisses, the valve itself is likely worn. Replace it — T&P valves should be replaced every 3–5 years as routine maintenance.
5. Place a bucket under the discharge pipe before testing or replacing the valve to catch any water.

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Cause 6: Ticking or Tapping From Pipes

Ticking and tapping sounds are often caused by thermal expansion — pipes expanding and contracting as hot water flows through them and rubs against pipe straps, joists, or walls. This is generally harmless but can be reduced.

1. Trace the ticking sound to its source along the hot water supply pipes.
2. Check pipe straps or hangers in the area — if a pipe is rubbing against a metal strap, wrap the contact point with adhesive foam pipe insulation to cushion it.
3. If pipes run through holes in joists, ensure the hole is large enough to allow the pipe to expand freely. If not, enlarge the hole slightly or add foam insulation around the pipe.
4. Installing an expansion tank on the cold water inlet can reduce thermal expansion pressure in a closed plumbing system.

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DIY vs. Professional Repair Cost Guide

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Frequently asked questions