Why Is My Water Heater Making Noise? Popping, Rumbling and More
Updated September 18, 2026
Can I do this myself?
DIY with precautions
Most noises are caused by sediment and are not dangerous in themselves. Flushing a tank is a reasonable DIY task if you follow the scald and power precautions carefully. Any discharge or leak from the temperature and pressure relief valve needs a professional.
Water heaters make a few noises as part of normal operation, but loud popping, rumbling or crackling usually points to sediment. Minerals in the water (calcium and magnesium, mostly) settle at the bottom of the tank over time. On a gas heater, and on the lower element of an electric one, water trapped under that layer turns to steam and bursts through it, which you hear as popping or rumbling, a bit like a kettle about to boil.
Sediment makes the heater work harder, reduces how much hot water you have and shortens the tank’s life. Flushing the tank can reduce the noise and slow that wear. It is a practical homeowner task, but the water coming out is hot enough to scald, and the heater must be switched off properly first so it doesn’t heat an empty tank.
Not every noise is sediment. Ticking is often just pipes expanding, while hissing, screaming or water around the temperature and pressure relief valve can signal a problem that needs a professional. This guide helps you tell them apart.
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Signs of the problem
- Popping or crackling when the heater is running
- Deep rumbling or a sound like boiling water
- Ticking or tapping from pipes on top of the heater
- Hissing or sizzling from the burner area or an electric element
- High-pitched whistling or screaming
- Hot water running out sooner, or rusty or cloudy hot water
- Water dripping from or around the relief valve pipe
Common causes
Sediment build-up
Most commonThe most common cause of popping and rumbling. Minerals collect on the tank bottom or around the lower element, trapping water that boils and bursts through. It is worse in hard-water areas and on tanks that have never been flushed.
Normal expansion and contraction
Most commonTicking or light tapping as the heater starts or stops is often metal pipes and heat-trap fittings expanding and cooling. It is usually harmless.
Condensation on the burner (gas)
SometimesSizzling on a gas heater can be condensation dripping onto the burner, especially when the tank is refilling with cold water. If it persists, or you see water pooling, a leak could be the cause.
Scale on an electric element
SometimesHissing or crackling on an electric heater can come from scale crusted on the heating element. Flushing helps; a badly scaled element may need replacing by a technician.
Pressure or relief valve problem
Less commonScreaming, whistling or water discharging from the temperature and pressure (T&P) relief valve can mean excessive pressure or temperature, or a failing valve. This is a safety device and needs professional attention.
Safety first: before you start
- Critical:If the temperature and pressure relief valve is leaking, dripping or discharging, don’t try to fix or replace it yourself. Call a licensed plumber.
- Critical:Before draining, switch off an electric heater at the breaker or fuse box, or set a gas heater’s control to Vacation, Pilot or Off exactly as the label instructs.
- Critical:Water from the drain valve can be scalding. Let the tank cool for a few hours if possible, wear gloves and eye protection, and keep children and pets away.
- Route the drain hose to a floor drain, outside to a spot where hot water won’t hurt plants, people or pets, or into buckets you can handle safely.
- Never switch the power back on to an electric heater until the tank is completely full, or the elements can burn out in seconds.
- If you smell gas near a gas heater, stop, leave and call your gas utility or emergency number from outside.
Tools & materials
Tools
- Garden hose long enough to reach a drain or outdoors
- Flat-head screwdriver (some drain valves open with one)
- Heat-resistant gloves and safety glasses
- Bucket
- Flashlight
Materials
- Old towels
- Replacement drain valve (only if yours is plastic and cracked, and you are confident fitting it)
Step-by-step fix
- 1
Identify the noise
Listen while the heater is heating. Popping and rumbling from the bottom point to sediment. Ticking at the pipes is usually normal. Screaming, whistling or water at the relief valve means stop and call a plumber rather than flushing.
- 2
Turn off the heat source
Electric: switch off the heater’s circuit at the breaker or fuse box. Gas: turn the gas control to Vacation, Pilot or Off, following the heater’s label. Don’t touch any other gas valves or fittings.
Warning: Never drain an electric heater with the power on. Exposed elements heat dry and can fail almost immediately.
- 3
Let the water cool if you can
Ideally, wait a few hours (or overnight) after turning off the heat so the water isn’t scalding. If you must drain sooner, treat the water as dangerously hot and keep the hose end secured away from people.
- 4
Shut off the cold water supply
Close the cold water inlet valve on the pipe feeding the top of the heater. Then open a hot water tap somewhere in the house, ideally on a lower floor, to let air into the system so the tank can drain.
- 5
Connect a hose and open the drain valve
Attach a garden hose to the drain valve at the bottom of the tank and run it to a floor drain, outside, or into buckets. Open the drain valve slowly. Water will be cloudy or gritty at first as sediment comes out.
Warning: Plastic drain valves on older heaters can be brittle. Open them gently. If one cracks and won’t close, close the cold supply valve fully and call a plumber.
- 6
Stir up sediment with bursts of cold water
Once the tank is mostly drained, briefly open the cold inlet valve for a few seconds, then close it again. This stirs up sediment on the tank bottom. Repeat a few times until the water from the hose runs fairly clear.
Tip: Checking the water in a clear jar or bucket makes it easy to see when it is running clean.
- 7
Close the drain and refill completely
Close the drain valve and remove the hose. Open the cold inlet valve fully. Leave the hot tap open until water flows steadily without spitting air, which means the tank is full. Then close the tap.
- 8
Restore heat
Only once the tank is full: switch the breaker back on for an electric heater, or return a gas heater’s control to On following the label. If the label requires relighting and gives homeowner instructions, follow them exactly; otherwise call a technician.
Warning: If you smell gas or the pilot won’t stay lit, don’t keep trying. Leave the controls off and call a qualified technician.
- 9
Check for leaks and listen
Check the drain valve and fittings for drips over the next hour. Once the water is back up to temperature, listen for the popping. It should be noticeably quieter. Heavy, long-term sediment may not fully clear in one flush.
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How to check it's fixed
- Popping and rumbling are reduced or gone once the heater is back to temperature
- The drain valve is closed and not dripping
- Hot water runs clear and lasts as long as it should
- No water around the relief valve or the base of the tank
When to stop and call a professional
- The temperature and pressure relief valve leaks, drips or discharges water or steam
- The heater screams, whistles or the tank itself is leaking
- You smell gas, see soot or scorch marks, or the pilot won’t stay lit
- The drain valve won’t open, won’t close, or has cracked
- Noise continues after flushing and hot water supply keeps getting worse
- The tank is old and rusty, or rusty water comes from the hot taps only
How to prevent it
- Flush the tank periodically as the manufacturer recommends, more often in hard-water areas.
- Consider a water softener or scale-reducing filter if your water is very hard.
- Have a plumber check the anode rod (which protects the tank from corrosion) every few years.
- Keep the thermostat at a moderate setting to slow scale build-up and reduce scald risk.
Frequently asked questions
Is a popping water heater dangerous?
Popping from sediment isn’t immediately dangerous, but it means the heater is working harder and wearing faster. Loud popping plus water at the relief valve, or a screaming sound, is different and needs a plumber.
How often should I flush my water heater?
Follow your manufacturer’s recommendation. Many suggest once a year, and more often in hard-water areas. Tanks that have never been flushed after many years may have hardened sediment that won’t fully clear.
What is the T&P valve and why is it leaking?
The temperature and pressure relief valve lets water escape if the tank gets too hot or pressurised, preventing a dangerous failure. A leak can mean high pressure, overheating or a worn valve. Testing and replacing it is a job for a licensed plumber.
Why does my water heater make a ticking noise?
Ticking is usually pipes, heat traps or the tank expanding and contracting as water heats and cools. It is generally harmless. Pipe insulation or looser pipe straps can reduce it.
Can flushing an old water heater cause a leak?
Sometimes. In very old tanks, sediment can be plugging weak spots, and old plastic drain valves can crack. If your tank is old and has never been flushed, consider having a plumber assess it first.
This guide is general information, not professional advice. Homes differ, so follow your product manuals and local codes. If anything looks different from what's described, or you feel unsure, stop and call a qualified professional. In an emergency, leave the area and call your local emergency number.
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