Hot Water System Making Noise: Popping, Hissing, Banging and Dripping

A hot water system making noise can be caused by normal heating, thermal expansion, dripping relief valves, sediment in the tank, high water pressure, water hammer, gas burner issues, heat pump fan noise, pipe movement, loose valves or a failing component. Some noises are minor, but popping, hissing, banging, rumbling, constant dripping or new loud noises should be checked before the system fails or becomes unsafe.

For Brisbane, Gold Coast and South East Queensland homes, noisy hot water systems are common in electric storage, gas storage, instant gas, heat pump and solar hot water systems. The key is working out whether the sound is normal operation or a sign of pressure, heating, gas, valve, pipework or cylinder problems.

JR Gas & Water supplies and installs hot water systems across Brisbane, the Gold Coast and South East Queensland, including electric, gas, heat pump and replacement hot water options.

Quick Answer: Why Is My Hot Water System Making Noise?

A hot water system may make noise because of:

• Normal heating and expansion

• Sediment buildup inside a storage tank

• Relief valve dripping or discharging

• High incoming water pressure

• Water hammer in the pipework

• Loose pipework or valves

• Thermostat or overheating issues

• Gas burner ignition problems

• Gas pressure problems

• Heat pump fan or compressor operation

• Faulty tempering valve

• Failing pressure limiting valve

• Expansion control valve noise

• Air in the pipework

• Tank corrosion or cylinder failure

• Faulty element in an electric system

• Blocked or restricted hot water pipework

A soft hum or occasional drip may be normal. Loud banging, popping, hissing, rumbling, steam, gas smell, electrical tripping or constant water discharge is not something to ignore.

Common Hot Water System Noises and What They Mean

Different noises point to different problems.

Popping

Popping is often linked to sediment buildup in storage tanks. Water trapped under sediment can heat, expand and make popping or cracking noises.

Hissing

Hissing may come from a leaking relief valve, pressure discharge, steam, gas leak, burner issue, pipe restriction or water spraying from a fitting.

Banging

Banging may be water hammer, pipe movement, pressure changes, loose pipework, fast-closing valves or sudden flow changes.

Rumbling

Rumbling may come from sediment inside the tank, gas burner issues, overheating or an ageing cylinder.

Dripping

Dripping may be normal relief valve discharge during heating, but constant dripping can point to high pressure, faulty valves or a failing hot water system.

Ticking or Clicking

Ticking can be normal metal expansion and contraction, especially as the tank heats and cools. Repeated clicking from controls may need checking.

Humming or Buzzing

Humming may come from electrical components, a heat pump compressor, fan operation, valves or vibration through pipework.

Gurgling

Gurgling may suggest air in the system, water movement, sediment, partial blockage or drain line issues.

Is Hot Water System Noise Normal?

Some hot water system noise can be normal.

Normal sounds may include:

• Minor expansion noises

• A heat pump fan operating

• Water movement through pipes

• Occasional relief valve drip during heating

• Soft clicking as metal expands or cools

• Low operating hum from some systems

• Burner operation on a gas unit

• Water refilling the tank after use

Noise is more concerning when it is:

• New

• Loud

• Constant

• Getting worse

• Linked to poor hot water performance

• Linked to leaking

• Linked to gas smell

• Linked to power tripping

• Linked to very hot water

• Linked to steam or heavy discharge

• Linked to banging through the house

If the noise has changed suddenly, the system should be inspected.

Popping Noise From a Hot Water System

A popping noise is common in storage hot water tanks when sediment builds up at the bottom of the cylinder.

Sediment may include:

• Minerals

• Scale

• Rust particles

• Dirt from pipework

• Tank debris

• Anode breakdown material

• Calcium buildup

As the element or burner heats the water, trapped water beneath sediment can boil or expand, creating popping sounds.

Popping may be more common in:

• Older storage tanks

• Electric storage systems

• Gas storage systems

• Systems with poor maintenance history

• Areas with scale concerns

• Tanks near end of life

• Systems that have been disturbed after water supply work

A small amount of noise may not mean immediate failure, but loud or worsening popping can suggest the tank needs inspection or replacement planning.

Rumbling Noise From a Hot Water System

Rumbling can also be caused by sediment buildup, but it may be more serious if the sound is deep, loud or ongoing.

A rumbling storage tank may indicate:

• Heavy sediment buildup

• Overheating under sediment

• Burner heat transfer issues

• Poor water circulation inside the tank

• Old cylinder condition

• Scale buildup

• Gas burner issues

• Internal tank wear

If a tank is old and rumbling heavily, replacement may be better value than repeated repairs.

JR Gas & Water can help assess whether a noisy system is repairable or whether replacement from the hot water systems range makes more sense.

Hissing Noise From a Hot Water System

A hissing sound needs attention because it can have several causes.

Possible causes include:

• Relief valve discharging

• Steam from overheating

• Water spraying from a small leak

• Pressure escaping from a valve

• Gas leak near a gas hot water system

• Burner or combustion noise

• Pipe restriction

• Faulty valve

• High water pressure

• Hot water escaping through a fitting

If hissing is accompanied by steam, very hot water, gas smell, visible leaking or unusual burner operation, stop using the system and arrange licensed help.

For suspected gas smell or gas leak near a gas hot water system, use JR Gas & Water’s gas leak repair service.

Banging Noise From a Hot Water System

Banging is often linked to pressure changes or water hammer.

Water hammer happens when water flow stops suddenly and creates a shockwave through the pipework.

It may be caused by:

• Fast-closing valves

• High water pressure

• Loose pipework

• Washing machine valves

• Dishwasher valves

• Mixer taps

• Hot water valves

• Pressure limiting valve issues

• Expansion control problems

• Poor pipe support

• Old pipework

Banging may seem like it is coming from the hot water system, but the cause may be elsewhere in the plumbing system.

JR Gas & Water can inspect hot water pipework and pressure issues through plumbing services across Brisbane and the Gold Coast.

Dripping Noise From a Hot Water System

A dripping noise may come from the relief valve, expansion control valve, drain line, fittings, cylinder, safe tray or nearby pipework.

Some dripping during heating can be normal. Constant dripping is not.

Dripping may be caused by:

• Normal thermal expansion

• Faulty relief valve

• High incoming water pressure

• Failed pressure limiting valve

• Failed expansion control valve

• Leaking fitting

• Cylinder corrosion

• Condensate from a heat pump

• Safe tray drain

• Leaking tempering valve

• Pipework leak

If the drip is constant, the system should be checked before water wastage or property damage worsens.

Ticking and Clicking Noises

Ticking and clicking can happen as metal expands and contracts while the system heats and cools.

This may be normal if:

• It only happens during heating

• It is soft and occasional

• There is no leak

• Hot water performance is normal

• The noise has not changed suddenly

Clicking may need checking if:

• It is constant

• Controls are clicking repeatedly

• Ignition is failing

• A gas unit keeps trying to start

• Electrical components are switching repeatedly

• Hot water temperature is inconsistent

• Error codes appear

Repeated clicking with failed ignition on a gas unit should be checked by a licensed gasfitter.

Heat Pump Hot Water Making Noise

Heat pump hot water systems naturally make some noise because they use a fan and compressor.

Normal heat pump noises may include:

• Fan noise

• Compressor hum

• Air movement

• Water circulation sounds

• Occasional defrost or control sounds depending on model

• Condensate dripping

Abnormal heat pump noises may include:

• Grinding

• Screeching

• Loud rattling

• Fan hitting debris

• Compressor knocking

• Sudden vibration

• Repeated fault cycling

• Noise much louder than usual

• Water leak noises separate from condensate

Heat pump placement matters. Poor location can make normal operating noise more noticeable to bedrooms, neighbours or outdoor living areas.

JR Gas & Water can help compare and install suitable heat pump and other hot water systems for Brisbane, Gold Coast and SEQ homes.

Electric Hot Water System Making Noise

Electric storage systems may make popping, ticking, humming, dripping or banging noises.

Common causes include:

• Sediment around the element

• Element heating noise

• Thermostat cycling

• Relief valve discharge

• High water pressure

• Water hammer

• Pipe expansion

• Faulty valve kit

• Overheating

• Cylinder corrosion

• Electrical fault

Electrical issues should be handled by a licensed electrician. Plumbing issues such as valves, pressure and leaks should be handled by a licensed plumber.

If the system is tripping power, repeatedly overheating or making unusual electrical buzzing, stop using it and arrange licensed help.

Gas Storage Hot Water System Making Noise

Gas storage systems can make burner noise, expansion noise, rumbling, popping or dripping sounds.

Common causes include:

• Burner operation

• Sediment in the tank

• Gas ignition issues

• Gas control problems

• Poor combustion

• Relief valve discharge

• High water pressure

• Overheating

• Old cylinder condition

• Gas pressure issues

• Flue or ventilation concerns

Gas smell, delayed ignition, popping on ignition or unusual burner noise should be treated seriously.

JR Gas & Water provides gas appliance installation, gas line installations and gas leak repair where gas hot water issues involve gas supply or appliance safety.

Instant Gas Hot Water Making Noise

Instant gas hot water systems can make operating noise as water flows, burners ignite and fans or controls run.

Normal sounds may include:

• Ignition click

• Burner start-up

• Fan noise

• Water flow through the unit

• Soft operating hum

Abnormal sounds may include:

• Loud banging on ignition

• Repeated clicking without ignition

• Hissing gas smell

• Whistling

• Rattling

• Loud vibration

• Popping inside the burner area

• Noise followed by error codes

• Noise when multiple outlets are used

Possible causes include:

• Gas pressure issue

• Incorrect gas line sizing

• Burner fault

• Fan fault

• Water flow issue

• Scale or restriction

• Appliance age

• Installation issue

• Gas valve problem

• Flue or combustion issue

Do not keep using an instant gas system that smells of gas or ignites with a bang.

Solar Hot Water System Making Noise

Solar hot water systems may make noise from tanks, pumps, valves, boosters or relief valves depending on the design.

Possible causes include:

• Normal expansion

• Pump operation

• Solar overheating

• Relief valve discharge

• Booster operation

• Air in the system

• Valve noise

• High pressure

• Heat transfer fluid issues in some systems

• Old cylinder condition

Heavy discharge, steam or very hot water from a solar system should be checked promptly.

Noise From the Relief Valve

The relief valve can make dripping, hissing or discharge noises.

This may happen because of:

• Normal thermal expansion

• Faulty relief valve

• High water pressure

• Overheating

• Expansion control valve issue

• Debris in valve seat

• Incorrect valve rating

• Old valve kit

• Cylinder pressure issues

A relief valve is a safety device. It should never be capped, blocked or ignored.

If the relief valve is constantly dripping, see JR Gas & Water’s hot water support through the hot water systems collection or book through the quote and booking page.

Noise From the Tempering Valve

A tempering valve blends hot and cold water to deliver safer water temperatures to fixtures.

A faulty or restricted tempering valve may cause:

• Whistling

• Humming

• Vibration

• Temperature fluctuation

• Poor hot water pressure

• Lukewarm water

• Intermittent noise when taps open

• Noise only on hot water outlets

If the noise happens only when hot taps are used, the tempering valve or hot water pipework may need checking.

Noise From the Pressure Limiting Valve

A pressure limiting valve controls incoming water pressure to the hot water system.

A faulty pressure limiting valve may cause:

• Humming

• Vibration

• Whistling

• Relief valve discharge

• Pressure fluctuations

• Water hammer

• Poor flow

• Repeated valve failure

If high pressure is the real issue, replacing the relief valve alone may not solve the noise.

Noise From Pipe Expansion

Hot water pipes expand as hot water passes through them. They can tick, creak or knock if they rub against framing, walls, clips, floors or cabinetry.

Pipe expansion noise may happen:

• When hot water first runs

• After a shower starts

• When the system reheats

• In wall cavities

• Under floors

• Near bathrooms

• Behind kitchens

• In ceiling spaces

This may be harmless, but loud banging or movement should be checked if it is new or worsening.

Noise From Water Hammer

Water hammer is a common cause of banging in homes.

It may be triggered by:

• Mixer taps

• Washing machines

• Dishwashers

• Toilet valves

• Solenoid valves

• Fast-closing outlets

• High water pressure

• Loose pipes

• Faulty pressure limiting valves

• Hot water valve issues

Water hammer can stress pipes, valves and fittings over time. If the banging is severe, pressure and pipe support should be checked.

Noise From Air in the Hot Water Pipes

Air in the pipes can cause spluttering, gurgling or irregular water flow.

Possible causes include:

• Recent plumbing work

• Water supply interruption

• Hot water system replacement

• Valve work

• Tank refilling

• Pipework changes

• Pumped water systems

• Rainwater supply issues

If the noise does not settle, or if pressure and flow are poor, the system should be inspected.

Noise From High Water Pressure

High pressure can cause several hot water noises, including:

• Hissing

• Banging

• Relief valve discharge

• Whistling

• Valve vibration

• Hammering

• Tap noise

• Pipe movement

High pressure can also shorten the life of:

• Relief valves

• Tempering valves

• Flex hoses

• Toilet inlet valves

• Mixer cartridges

• Hot water cylinders

• Appliance valves

JR Gas & Water can check pressure issues as part of plumbing services across Brisbane and the Gold Coast.

Noise From Sediment in the Tank

Sediment is a common cause of popping and rumbling in storage tanks.

Sediment can reduce performance by:

• Insulating the heating surface

• Creating hot spots

• Increasing heating noise

• Reducing effective tank volume

• Contributing to corrosion risk

• Making the system work harder

• Causing uneven heating

• Increasing wear on the tank

In an older tank, heavy sediment can be a sign the system is nearing replacement age.

Noise From Overheating

Overheating can create hissing, steaming, banging or heavy relief valve discharge.

Possible causes include:

• Thermostat fault

• Gas control fault

• Electrical element issue

• Solar overheating

• Control failure

• Incorrect settings

• Faulty safety device

Overheating is not normal. If water is extremely hot, the relief valve is discharging heavily, or steam is present, stop using the system and arrange urgent licensed help.

Noise and Gas Smell Together

If a gas hot water system is noisy and you smell gas, treat it as a safety issue.

Possible causes include:

• Gas leak

• Delayed ignition

• Gas valve issue

• Burner fault

• Incorrect gas pressure

• Poor combustion

• Regulator problem

• Appliance fault

• Pipework leak

If you smell gas:

• Do not keep using the appliance

• Avoid flames and ignition sources

• Turn off gas if safe

• Move people away if the smell is strong

• Call emergency services if there is immediate danger

• Arrange licensed gas help

JR Gas & Water provides gas leak repair services across Brisbane and the Gold Coast.

Noise and Electrical Tripping Together

If an electric or heat pump hot water system is noisy and tripping power, it needs licensed attention.

Possible causes include:

• Failed element

• Faulty thermostat

• Water ingress

• Electrical fault

• Overheating

• Heat pump component fault

• Damaged wiring

• Safety switch trip

• Short circuit

Do not keep resetting the breaker without diagnosing the cause. Electrical faults need a licensed electrician.

Noise and Leaking Together

Noise plus leaking is more concerning than noise alone.

Possible causes include:

• Relief valve fault

• High pressure

• Cylinder leak

• Valve kit leak

• Overheating

• Corroded fittings

• Heat pump condensate mistaken for leak

• Cracked pipework

• Failed union or valve

If water is at the base of the tank, the cylinder may be failing. If water is coming from the relief valve drain line, the valve kit or pressure may need checking.

Noise and Poor Hot Water Performance

Noise combined with poor hot water performance may suggest the system is struggling.

Possible signs include:

• Water not hot enough

• Hot water running out faster

• Temperature fluctuating

• Long recovery time

• Error codes

• Burner cutting out

• Heat pump not completing heating

• Electric element fault

• Sediment reducing efficiency

• Gas pressure issue

• Tempering valve problem

A noisy system that also performs poorly should be inspected before failure.

Should You Repair or Replace a Noisy Hot Water System?

The decision depends on the cause, age and condition of the system.

Repair May Make Sense When

Repair may suit if:

• The system is not too old

• The noise is from a replaceable valve

• Pressure can be corrected

• Pipework can be secured

• A tempering valve is faulty

• A pressure limiting valve is failing

• Minor component repair is available

• The cylinder is in good condition

• Hot water performance is otherwise good

Replacement May Be Better When

Replacement may be better if:

• The tank is old

• The cylinder is corroded

• Water is leaking from the tank

• Sediment noise is severe

• Multiple components are failing

• Repairs are becoming frequent

• Parts are unavailable

• The system is inefficient

• Hot water demand has outgrown the unit

• Gas or electrical safety faults are present

• The system has reached the end of practical life

JR Gas & Water can help compare repair versus replacement and supply suitable hot water systems where replacement is the better option.

When Is Hot Water System Noise Urgent?

Hot water system noise should be treated urgently if:

• There is gas smell

• There is steam

• Water is extremely hot

• Relief valve is pouring heavily

• The system is banging loudly

• Power is tripping

• Water is leaking from the tank

• The cylinder is rusted or bulging

• The hot water unit is making new loud noises

• The system is outside a bedroom and suddenly much louder

• A heat pump fan is grinding or scraping

• The unit is showing error codes

• The system has stopped producing hot water

• Water is damaging property

If there is immediate danger, isolate the system only if safe and arrange urgent licensed help.

What Homeowners Can Check Safely

You can observe without working on the system.

Check:

• What type of noise is it?

• When does it happen?

• Does it happen during heating?

• Does it happen when taps are used?

• Is water leaking?

• Is the relief valve dripping?

• Is there steam?

• Is there gas smell?

• Is power tripping?

• Is hot water too hot or not hot enough?

• Is the system electric, gas, heat pump or solar?

• How old is the system?

• Has the noise suddenly changed?

• Does the noise happen at every tap or only one outlet?

• Are pipes banging elsewhere in the home?

A short video of the noise can help the plumber understand what is happening.

What Not To Do

Avoid these unsafe mistakes:

• Do not ignore gas smell

• Do not keep using a system that is steaming

• Do not cap or block relief valve discharge

• Do not keep resetting electrical trips

• Do not open gas components yourself

• Do not remove hot water valves yourself

• Do not adjust gas pressure yourself

• Do not assume loud banging is harmless

• Do not ignore water around the tank base

• Do not drain scalding hot water where people can be burnt

• Do not attempt electrical repairs

• Do not replace safety valves without a licensed plumber

• Do not assume every noise means the same fault

Hot water systems involve pressurised hot water, electricity and sometimes gas. Licensed trades should diagnose and repair them.

Brisbane Hot Water Noise Considerations

Brisbane homes may have older electric storage systems, gas hot water, heat pumps, high-set pipework and homes with pressure or water hammer issues.

Common Brisbane noise causes include:

• Older storage tanks with sediment

• Relief valve dripping during heating

• Water hammer in older pipework

• High pressure affecting valve kits

• Gas hot water ignition noise

• Heat pump placement near bedrooms

• Pipe expansion under high-set homes

• Noisy systems in garages or side access

If the noise is new or worsening, have the system checked before it becomes a leak or failure.

Gold Coast Hot Water Noise Considerations

Gold Coast homes may deal with coastal exposure, heat pumps, apartments, outdoor systems, LPG gas hot water and body corporate access.

Common Gold Coast noise causes include:

• Corroded external fittings

• Heat pump fan or compressor noise

• Relief valve discharge on exposed systems

• LPG gas hot water burner noise

• Apartment safe tray drains

• Water hammer in townhouses

• Outdoor units affected by salt and weather

• Noisy systems close to bedrooms or neighbours

Coastal exposure can make external valves and fittings age faster.

Acreage and Rural SEQ Hot Water Noise Considerations

Acreage properties may use LPG, electric storage, heat pumps, rainwater, pumps and long pipe runs.

Noise may be linked to:

• Pump pressure

• Air in pipes

• Rainwater sediment

• Valve kit wear

• LPG gas pressure

• Long pipe movement

• Storage tank sediment

• Heat pump placement

• Outdoor exposure

• Pressure control setup

Homes on rainwater or pumped supply may need pressure and filtration considered as part of diagnosis.

Rental Property Hot Water Noise

For rentals, noisy hot water systems should be checked if tenants report:

• Loud banging

• Constant dripping

• No hot water

• Water too hot

• Gas smell

• Power tripping

• Noise waking occupants

• Leaks around the unit

• Heat pump noise complaints

• Hot water running out quickly

Early inspection can prevent larger property damage and tenant complaints.

What To Send When Booking

Helpful information includes:

• Photos of the hot water system

• Photo of model label

• Short video of the noise

• Description of the sound

• When the noise happens

• Whether hot water still works

• Whether water is leaking

• Whether relief valve is dripping

• Whether there is gas smell

• Whether power is tripping

• System type: gas, electric, heat pump or solar

• Approximate system age

• Property suburb

• Access details

Send these through the JR Gas & Water quote and booking page to help identify the right service pathway.

How JR Gas & Water Can Help

JR Gas & Water can help diagnose noisy hot water systems, check valves and pressure, inspect leaks, replace failed systems and advise on repair versus replacement across Brisbane, the Gold Coast and South East Queensland.

Depending on the issue, this may involve:

• Checking whether the noise is normal operation

• Inspecting relief valve discharge

• Checking pressure limiting valves

• Checking tempering valves

• Looking for leaks

• Checking cylinder condition

• Investigating water hammer

• Assessing heat pump noise and placement

• Checking gas hot water symptoms

• Recommending gas leak repair where needed

• Advising when repair is practical

• Replacing old or failing hot water systems

• Coordinating licensed electrical or gas work where required

For replacement options, view JR Gas & Water’s hot water systems. For gas-related hot water concerns, JR can also help with gas appliance installation, gas line installations and gas leak repair.

FAQs About Noisy Hot Water Systems

Why is my hot water system making a popping noise?

Popping is often caused by sediment buildup inside a storage tank. Water trapped under sediment can heat and expand, creating popping or cracking sounds.

Why is my hot water system hissing?

Hissing may come from a relief valve, pressure discharge, steam, leaking water, gas leak, valve issue or burner problem. If there is gas smell or steam, stop using the system and arrange urgent licensed help.

Why does my hot water system bang?

Banging is often caused by water hammer, high pressure, pipe movement or fast-closing valves. It may also be linked to hot water valve or pressure issues.

Is dripping from a hot water system normal?

A small amount of relief valve discharge during heating can be normal. Constant dripping, heavy discharge or water around the tank base should be checked.

Is heat pump hot water noise normal?

Some fan and compressor noise is normal. Grinding, scraping, loud rattling or sudden noise changes are not normal and should be inspected.

Can a noisy hot water system be dangerous?

It can be, depending on the cause. Gas smell, steam, overheating, electrical tripping, heavy discharge or loud banging should be treated seriously.

Should I repair or replace a noisy hot water system?

Repair may suit valve, pressure or minor component faults on newer systems. Replacement may be better for old, corroded, leaking, heavily sedimented or unreliable systems.

Who should check a noisy hot water system?

A licensed plumber should check valves, pressure, leaks and cylinder condition. Gas issues need a licensed gasfitter, and electrical issues need a licensed electrician.

Final Word

A hot water system making noise can be harmless, but it can also be an early warning sign. Popping, hissing, banging, rumbling, dripping, clicking, humming or gurgling can point to sediment, pressure problems, relief valve issues, water hammer, gas faults, heat pump operation, overheating or a failing cylinder.

The safest approach is to look at the pattern: when the noise happens, whether water is leaking, whether hot water performance has changed, whether gas smell is present and whether the system is old.

JR Gas & Water can help inspect noisy hot water systems, check valves and pressure, identify repair options and replace failing systems across Brisbane, the Gold Coast and South East Queensland.

Book JR Gas & Water before a strange hot water noise turns into a leak, cold shower, gas fault or full system failure.