Hot Water Not Working? Here’s Why (& How to Fix it)

Your hot water not working can disrupt your whole day—showers, dishes, laundry, everything. This guide is for Canberra homeowners experiencing hot water issues. It covers common causes, troubleshooting steps for electric, gas, and continuous-flow systems, and when to seek professional help. Canberra Plumbing & Drains provides fast diagnosis and licensed hot water repairs across Canberra, for electric, gas, and continuous-flow systems. Prompt professional repairs are essential to ensure the safe operation of your hot water system and to prevent further damage.

If there’s a strong gas smell (often described as a “rotten egg” odour), treat it as an emergency: get to a safe place and call the gas emergency line on 1800 GAS LEAK (1800 427 532).​

Hot water not working (start here)

Before assuming the unit has failed, do these quick checks:

• Check if the issue is at all hot taps or only one tap (a single outlet can be a tap/valve issue, not the heater).
• If only one tap is cold, the problem is likely a localised fixture or a faulty tempering valve. (A tempering valve blends hot and cold water to deliver water at a safe temperature. A localised fixture means the issue is likely with that specific tap or its piping, rather than the heater.)
• Check whether your system is electric, gas storage, or continuous-flow/instant (the “right” troubleshooting depends on the type).​
• If you have an electric system, check the switchboard—some people find the breaker “doesn’t look tripped,” so switching it fully OFF then ON can be a useful first step. A tripped circuit breaker is a common cause of hot water not working, so always check and reset it. Also, make sure the power supply to the hot water system is switched on.
• Check other gas appliances to confirm your home has gas service.

Identifying the root cause of the hot water problem is essential for effective repairs and to determine whether you can fix it yourself or need professional help.

Stop and call a professional immediately if:

• You smell gas or suspect a gas leak.​
• The circuit breaker/safety switch keeps tripping repeatedly (this can indicate a serious electrical fault).​
• You can see water leaking near electrical components or pooling around the unit.​

Why is my hot water not working properly?

In most homes, “no hot water” comes down to one of three categories:

• The unit can’t heat water (electrical element/thermostat issues in electric systems, or burner/ignition issues in gas systems).​
• The unit can’t detect demand or can’t run correctly (common in continuous-flow systems if flow is too low).​
• A leak, installation issue, or safety control is forcing the system to shut down to prevent damage.​

The most common causes of no hot water include power or gas supply issues, a tripped breaker, the pilot light going out (for gas systems), a faulty thermostat or heating element (for electric systems), or sediment buildup in the tank.

Sediment buildup in the tank can lead to hot water system failure and should be addressed as part of regular maintenance. Regular maintenance, such as inspecting components, removing sediment buildup, and replacing worn parts, helps ensure optimal performance and reliability of your hot water system.

Inspect the base of the tank and pipe connections for significant water pooling, which may indicate a leak or other issue.

When booking a repair, it helps to note: “no hot water at all” vs “lukewarm,” any error lights/codes, any recent storms/power outages, and whether the issue started suddenly or gradually.

Problem #1: Faulty or damaged heating element (and thermostats)

Electric storage hot water systems rely on heating components and controls to heat the tank. Common causes of issues include faulty thermostats and a faulty heating element, which can result in lukewarm water, water that runs cold quickly, or temperature swings. The upper heating element and lower element both play crucial roles in heating water properly and maintaining a consistent hot water supply. If either element fails, corrodes, or develops loose connections, the system may not heat water efficiently. Electrical issues, such as loose connections or other faults, can also cause inconsistent heating or complete system failure.​

What can be checked safely:

• Confirm the unit has power at the switchboard (and that it hasn’t been inadvertently switched off).
• If power keeps tripping back off, stop and book a licensed electrician/plumber rather than repeatedly resetting.​

Human example: a common call-out is “it worked after a reset once, then stopped again”—that pattern often points to an underlying fault rather than a one-off glitch.​

Problem #2: Water leak

Leaks don’t just waste water—they can affect performance and create safety risks. Some guides flag that pooling water, dripping, or leaks around the system can signal the heater or connected components are compromised. Leaks may also originate from the water heater tank itself, or be caused by a faulty pressure relief valve or issues with the relief valve. A faulty pressure relief valve can cause leaks in the hot water system. Additionally, a corroded anode rod should be replaced to prevent further damage to the water heater tank.

What to do:

• If it’s safe, avoid using hot water until the leak is assessed (continued operation can worsen damage).
• Book an inspection to identify whether the leak is from valves/pipework or the tank itself.

Human example: many “no hot water” jobs begin with “we noticed a small puddle last week”—catching it early can prevent a bigger breakdown.

Problem #3: Improper installation (or the system is undersized)

If the hot water unit is too small for your household or incorrectly set up, it may feel like “hot water not working” because it can’t keep up. Insufficient tank size or storage tanks can result in not having sufficient hot water or stored hot water available between heating cycles, especially after lifestyle changes (extra occupants) or renovations (bigger showers, added bathrooms).

What to do:

• A plumber can assess demand, recovery time, and whether a repair vs upgrade is the best value. Licensed plumbers can also provide guidance on the most efficient and cost-effective replacement options, especially since most hot water systems last 8–12 years and older units may need replacement if they frequently fail.
• If the unit is in an unsuitable location or set up poorly, correcting the install can improve reliability and running costs.
• Regular maintenance and proper management of the heating cycle and storage tanks can help extend the lifespan of your hot water system and ensure safe, efficient operation.

Human example: “It was fine when we moved in, then we renovated the bathroom—now we always run out.”

Problem #4: Pilot light issues (gas hot water)

Gas storage systems can stop heating if the pilot light goes out or ignition fails. In a gas hot water heater, the thermocouple acts as a safety device that monitors the pilot light and controls gas flow. If the thermocouple is not functioning properly, it may mistakenly shut off the gas supply even if the pilot light is still burning. A common troubleshooting approach in gas-focused guides is: check the gas supply/valve position, then follow the manufacturer lighting procedure, then escalate if the pilot won’t stay lit.​

What to do:

• Follow the instructions on your unit (or inside the access panel) for relighting if you’re confident and it’s safe to do so.
• If it repeatedly goes out, book a licensed gas plumber to test and repair the cause.

Human example: “It lights, but won’t stay on” is a frequent symptom that needs proper diagnosis.

Problem #5: Natural gas leak (urgent)

If you smell gas, prioritise safety over troubleshooting. A natural gas leak can interrupt the functioning of a gas hot water heater. If you have no hot water and notice an odour like rotten eggs, this may indicate a natural gas leak.

The smell of rotten eggs is a warning sign—if you detect it, turn off the gas supply, evacuate the area, and contact your gas provider or gas utility company immediately. Australian Gas Networks advises calling Gas Leaks and Emergency services on 1800 GAS LEAK (1800 427 532) immediately if you smell gas or are concerned about gas appliance safety.​

Do not delay to “see if it goes away”—leave the area and make the call.

How to Fix Gas & Electric Hot Water System Problems (Safe Checks)

Check All Taps

• Check if the issue is with just one hot water tap or all taps. If only one tap is cold, the problem is likely a localised fixture or a faulty tempering valve. (A tempering valve blends hot and cold water to deliver water at a safe temperature. A localised fixture means the issue is likely with that specific tap or its piping, rather than the heater.)
• Test multiple hot taps and compare with other taps in the house.

Check Water Flow and Pressure

• Check water flow and water pressure at the affected taps.
• Low pressure or poor water flow may indicate issues with the pressure regulator, mineral buildup in the plumbing system, or a blockage in the hot water tap.
• If you notice low pressure across the plumbing system, it could also be due to a faulty pressure regulator or airlocks.

Electric System Checks

• Check the switchboard and reset once if appropriate—if it trips again, stop and book a professional.
• For electric water heater troubleshooting, inspect for issues with heating elements, leaks, or system failures.
• If unsure, contact a professional plumber.

Continuous-Flow System Checks

• Ensure you’re running enough flow—Rinnai notes some units won’t activate below a minimum flow rate (e.g., 2.5 L/min).
• Check for inlet filter obstructions.

Gas System Checks

• If you’re comfortable and it’s safe, check the unit’s instructions for pilot/ignition steps.
• Escalate if it won’t relight or won’t stay lit.

If water supply or flow issues persist, or if you suspect problems with the pressure regulator, mineral buildup, or the plumbing system, call a professional plumber or qualified plumber for diagnosis and repair.

Need your whttps://canberraplumbing.net.au/plumbing-tips/fix-water-pressure-problems/ater heater fixed? Call Canberra Plumbing & Drains

If your hot water is not working, book a licensed professional plumber to diagnose it properly and get it fixed safely. A professional plumber can accurately diagnose hot water problems and make safe, lasting repairs. Canberra Plumbing & Drains can help with repairs, maintenance, and replacement advice for gas and electric hot water systems across Canberra.

Call (02) 6288 9929 or use the contact form to request a priority booking.

FAQs (hot water not working)

Why do I have no hot water in the whole house?

Common causes of a hot water problem affecting your household’s hot water supply include:

• Loss of power to an electric unit
• A safety trip
• A gas/pilot ignition issue depending on system type
• Power or gas supply issues
• A tripped breaker
• The pilot light going out (for gas systems)
• A faulty thermostat or heating element (for electric systems)
• Sediment buildup in the tank

Identifying the root cause is essential for restoring reliable hot water throughout your home.

The breaker doesn’t look tripped—should I still reset it?

Some homeowners report breakers can appear “not tripped,” so switching fully OFF then ON can help confirm.​

A tripped circuit breaker or an interrupted power supply is a common cause of hot water not working. Always check that the power supply to your hot water system is switched on and functioning properly, and reset the circuit breaker if necessary.

My safety switch keeps tripping—can I keep resetting it?

Repeated tripping is a “stop and call” sign, and trade guidance warns it can indicate dangerous faults like wiring or grounded components. Repeated tripping may also point to electrical issues within the hot water system, so it’s important to consult a qualified electrician to safely diagnose and repair the problem.

My continuous-flow system runs cold unless I turn the tap up—why?

Some continuous-flow units may not activate below a minimum flow rate, so low-flow use can prevent heating from starting. Other possible causes include:

• Insufficient water flow or low water pressure—often caused by blockages or faulty pressure limiting valves
• Blockages or mineral buildup in the plumbing system
• Faulty pressure regulator or airlocks

If you notice low pressure or poor water flow from your hot water tap, it may be necessary to check your water pressure or consult a plumber to resolve the issue.

What should I do if I smell gas?

If you have no hot water and notice an odour like rotten eggs, this may indicate a natural gas leak. The smell of rotten eggs is a warning sign added to natural gas for safety. If you smell natural gas:

1. Turn off the gas supply
2. Evacuate the area
3. Contact your gas utility company immediately

Leave the area and call the gas emergency line—Australian Gas Networks lists 1800 GAS LEAK (1800 427 532) for gas leaks and emergencies.​

Is a pilot light going out a big deal?

It can be; if it won’t stay lit or fails repeatedly, it typically needs a licensed diagnosis rather than repeated relighting attempts.​ In gas water heaters, the thermocouple acts as a safety device that detects whether the pilot light is burning. The thermocouple must be functioning properly to keep the gas supply on when the pilot light is burning. If the thermocouple is not functioning properly, it may mistakenly shut off the gas supply even if the pilot light is still burning.

When do I need an electrician instead of a plumber?

If the issue involves:

• Electrical supply faults
• Repeated breaker trips
• Internal electrical testing
• Suspected electrical issues such as loose connections

A qualified electrician may be required for safe diagnosis and repair (and many repairs involve coordination).​​