No hot water is one of the most common calls we get, and it always seems to happen at the worst possible time. The good news is that a surprising number of “no hot water” problems have a simple cause you can check yourself in a few minutes, safely, before you pay for a callout. This guide walks you through what to check for each type of system, what the signs mean, and when it is time to call a plumber.
Safety first: when to stop and call straight away
Before you check anything, stop and call a licensed plumber if any of these apply:
- You can smell gas. Turn the gas off at the meter, do not use switches or flames, and call us on 0499 914 900. If the smell is strong or anyone feels unwell, call the gas network’s emergency line first.
- Water is leaking from the bottom of the tank. This usually means the tank itself has failed. Turn off the cold water supply to the system and switch off its power or gas.
- There are scorch marks, a burning smell or a tripped switch that trips again straight away. Leave the power off.
- The relief valve is pouring water or steam continuously. A small drip is normal. A steady flow is not.
Never remove covers or panels on an electric or gas hot water system. There are live electrical parts and gas components behind them, and that work must be done by a licensed tradesperson.
Why do I have no hot water? The quick checks
Start with the questions that narrow it down fastest:
- Is it every hot tap, or just one? If only one tap or shower is cold, the hot water system is probably fine and the problem is that tap’s mixer or cartridge.
- Is the hot water completely cold, or just lukewarm? Completely cold points to the heater not running. Lukewarm points to a thermostat, element, tempering valve or a system that simply ran out.
- Have you used a lot of hot water recently? Several showers in a row or visitors staying can empty a storage tank. Give it a few hours to recover before assuming it is faulty.
- What type of system do you have? The checks below depend on it.
No hot water from an electric hot water system
Electric storage tanks are the most common system in older Mandurah homes. Check these in order:
- The switchboard. Look for a tripped circuit breaker or safety switch labelled hot water or HWS. Reset it once. If it trips again, leave it off and call us.
- The off-peak timer. Some systems only heat overnight on a separate tariff. If the tank ran out during the day, it may not reheat until the next heating period.
- The isolation switch. Many units have a switch near the tank. Make sure it has not been turned off.
If the power is on and there is still no hot water, the heating element or thermostat has most likely failed. Both are common repairs on a tank that is otherwise in good condition, and we can usually tell you on the spot whether repairing it is worth it or whether the tank is near the end of its life.
No hot water from a gas hot water system
Gas storage systems: check whether the pilot light is still lit through the viewing window. Wind, a gust through the enclosure or a supply interruption can blow it out. Follow the relighting instructions printed on the unit only if you are comfortable doing so. If it will not stay lit, the thermocouple or gas control is often the cause, and that needs a licensed gas fitter.
Continuous flow (instantaneous) gas systems: these need power as well as gas. Check the power point the unit plugs into and the switchboard. Many have a controller inside the house that shows an error code, which is worth noting down before you call. If you are on bottled gas, check the bottles have not run empty, which is one of the most common causes we see.
Also check whether your gas stovetop is working. If it is not, the problem is the gas supply, not the hot water system.
No hot water from a solar or heat pump system
Solar hot water: after a run of cloudy days, the electric or gas booster does the heating. If the booster is switched off or its circuit has tripped, the water will only be as warm as the sun made it. Check the booster switch and its breaker at the switchboard.
Heat pump systems: check the power and look for an error light or code on the unit. Make sure the fan area is not blocked by leaves or stored items, as heat pumps need clear airflow to work. If you have a timer set to run only during the day, the tank may have run out overnight after heavy use.
Why is my hot water lukewarm?
Lukewarm water that never gets properly hot usually comes down to one of these:
- A failing thermostat or heating element on an electric system
- A faulty tempering valve, which mixes hot and cold water to keep your taps at a safe temperature
- Sediment built up in the bottom of the tank, which reduces how much hot water it can hold
- A system that is too small for the number of people now living in the house
These are worth getting checked sooner rather than later. A system that is struggling often fails completely not long after.
Is it time to repair or replace?
As a rough guide, most storage hot water systems last around 8 to 12 years, depending on the type and local water quality. If your system is in that range and is now leaking, rusting at the base or failing repeatedly, replacement is usually the better value. A newer system will also cost less to run.
If you are replacing, it is worth considering an upgrade rather than a like-for-like swap. Our guide on whether a heat pump is worth it in WA explains the running cost savings and the rebate that applies. You can also browse our gas, electric, solar and heat pump hot water systems.
Need hot water back today?
We take emergency calls across Mandurah and the Peel region, including Halls Head, Falcon, Dawesville and Meadow Springs. Call 0499 914 900 and tell us what type of system you have, whether it is completely cold or lukewarm, and anything you have noticed. We will tell you straight away whether it needs someone out now or can safely wait. See all our plumbing and hot water services in Mandurah.
No hot water FAQs
Why is my hot water not working but my cold water is?
The hot water system itself has usually stopped heating. On an electric system check for a tripped breaker, on gas check the pilot light or gas supply, and on a continuous flow unit check the power and any error code on the controller.
How long does a hot water system take to heat up again?
An electric storage tank can take several hours to fully reheat, and off-peak systems may only reheat overnight. Gas storage recovers faster, and continuous flow gas heats water on demand.
Can I reset my hot water system myself?
You can safely reset a tripped circuit breaker once at the switchboard. If it trips again, leave it off and call a plumber. Never open panels or covers on the unit itself.
Why do I have no hot water in only one shower?
If other hot taps work, the hot water system is fine. The problem is usually the mixer, cartridge or valve on that particular shower or tap.
Is no hot water an emergency?
It is urgent if water is leaking from the tank, you can smell gas, or a switch keeps tripping. Otherwise it is inconvenient rather than dangerous, and a plumber can advise whether same-day repair is needed.
Talk to a licensed Mandurah plumber
Call Andrew and the team at Mandurah Hot Water, or send us a message and we will come back to you.
