Why Is My Hot Water Not Working? (Troubleshooting)

So your hot water's gone cold and you're standing there staring at the tap like it owes you money. Look, it happens. Most of the time it comes down to a handful of things — a tripped switch or a cooked element if you're on electric, or the pilot light's gone out if you've got gas. Before you start pulling your hair out though, work out if it's the whole house that's gone or just the one tap. Have a squiz at the safe checks below. Some of these are dead obvious, honestly, but anything involving gas, wiring or a tank that's leaking — that's when you pick up the phone and get someone licensed. Don't muck around with that stuff.

First, narrow it down

Don't touch a thing until you know what's actually going on. Here's the breakdown:

• No hot water anywhere? Then it's the hot water system itself causing the headache.

• No hot water at just one tap? Probably a tap, mixer or valve going wrong — see our tap and fixture repairs.

• Lukewarm or running out fast? That's pointing at a thermostat, element, or a system that's getting old or was maybe too small to start with.

• Discoloured or smelly hot water? Tank could be corroding from the inside — have a read of how long hot water systems last.

Electric hot water troubleshooting

Electric unit? Right, here's what to poke around at safely before you ring anyone:

• Check the switchboard. A tripped breaker or safety switch is hands down the most common thing we come across. Flick it back on, just the once. If it trips again straight away though — stop. That's a fault that needs an electrician or plumber, not you sitting there resetting it over and over hoping for the best.

• Check the isolation switch. Plenty of electric units have their own switch sitting near the unit or up by the switchboard. Make sure it's actually on. You'd be surprised how often someone's knocked it off by accident.

• Consider your tariff. Off-peak or controlled-load systems only heat at certain times of day. If the household's had a big morning of showers and laundry, you might just be waiting for the next heating cycle — that's not a fault, that's just timing.

• Look for leaks. Any water pooling round the bottom of the unit? That's a tank problem — turn it off at the switch and call a plumber straight away.

Power's on, no leaks, still freezing cold showers? You're probably looking at a failed element or thermostat. Both of those sit inside the unit and involve live electrical bits, so they really do need a licensed professional to test and swap them — don't go cracking it open yourself.

Gas hot water troubleshooting

Running gas? Check these things first before you do anything else:

• Is the gas on? Double check the supply's actually on at the meter and at any isolation valve near the unit. If your other gas appliances aren't working either, then it's a supply issue, not something wrong with the unit itself.

• Check the pilot light (on older storage units). Gone out? Follow the relighting instructions on the unit — exactly as they're printed on there. Won't stay lit, or you catch even a small whiff of gas at any point, stop what you're doing and ring a licensed gas fitter.

• Continuous-flow units usually flash an error code on a little display or controller. Jot the code down — helps the plumber figure out the fault way quicker when you call.

• Check for a tripped controller if your continuous-flow unit's got one of those temperature controllers with its own power supply attached.

Important: smell gas at any point and it's an emergency. Don't try relighting anything — follow our guide on what to do in a gas leak and ring a licensed gas fitter immediately.

Those continuous-flow error codes are actually pretty useful, so write the code down before you hit reset or call anyone. Different codes mean different things — ignition failure, water-flow problem, overheating, sensor's gone — and giving the plumber the code over the phone usually means they turn up with the right part first time instead of having to make a second trip.

Checks that apply to both

A handful of causes hit gas and electric systems the same way, so run through these before you assume the worst:

• Cold snap? When it gets properly cold outside, heating takes longer. Outdoor units especially can struggle a bit with it. Water coming into the tank is colder so the system just has more work to do, simple as that.

• Recently ran out? A storage tank that's been emptied by a stack of use — back-to-back showers, washing machine running hot — just needs time to refill and reheat. Not a fault. Just capacity.

• Blocked or closed valve? Make sure the cold water supply to the unit is actually turned on. If someone's done work nearby recently they might've left a valve shut without thinking.

• Been away? Some systems get switched off or run right down over a holiday and just need time to come back up to temp once you're home.

Not enough hot water, rather than none?

Getting some hot water but it runs out too quick or never really gets properly hot? That's usually a different problem to a total failure. Could be a thermostat set too low, a partially failed element — electric units often have two elements and one can go while the other keeps chugging along — sediment build-up that's shrinking the tank's actual usable space, or sometimes the system's just gotten too small for your household now. A plumber can test which one it is and tell you if you're better off repairing it or resizing to something bigger.

When to call a plumber

Call a licensed plumber or gas fitter if:

• The circuit breaker trips repeatedly

• The pilot light won't stay lit

• You see water leaking from or pooling around the unit

• The water is discoloured, rusty or smells off

• A continuous-flow unit shows a persistent error code

• You smell gas at any point — stop and call immediately

Elements, thermostats, gas valves and tank leaks — these all need a licensed person. It's not just about doing the job right either. Over here in WA, gas work and most plumbing legally has to be carried out by someone licensed, which we go through in do I need a licensed plumber in WA.

Still no hot water after going through all this? Call our licensed Canning Vale plumbers and we'll sort it out safely. For repairs and replacements, see our hot water systems service.

Frequently asked questions