No Hot Water? 7 Common Causes and How to Fix Them
When you turn on the tap and get nothing but cold, it's almost always one of these seven things. I'll walk you through what to check and when to call me.
I got a call from a house in Mosman a while back. Family of four, no hot water for two days. The husband had reset the breaker three times, and each time it tripped again within a couple of hours. "I kept flipping the switch but it kept tripping," he said. I opened the access panel, tested the element with a multimeter, and found a corroded heating element that was shorting out. Forty-five minutes later they had hot water again. Cost him way less than a new hot water system.
Here are the seven causes I see most often, listed from easiest to check to most serious.
- Tripped circuit breaker. Electric hot water draws serious current. A power surge, faulty element, or water ingress trips the breaker labelled "hot water" or "HWS" on your switchboard. Reset it fully off then back on. If it trips again within hours, you've got a faulty element or wiring issue.
- Faulty heating element. The element sits inside the tank and heats the water. Over time it corrodes, especially once the sacrificial anode is depleted. When it fails you get lukewarm or cold water. I can swap one in under an hour.
- Pilot light out. Gas systems use a pilot light to ignite the burner. Wind, a draft, a failing thermocouple, or a gas interruption blows it out. Follow the manufacturer instructions to relight it safely. If it won't stay lit, the thermocouple is your problem.
- Sediment buildup. Minerals from Sydney's water settle at the bottom of the tank. They create an insulating layer that stops the element from heating properly. You'll hear rumbling or popping noises. Annual flushing prevents this.
- Failed thermocouple. This little sensor detects whether the pilot is burning. When it fails, the gas shuts off even though the pilot is lit. Cheap part, thirty-minute swap, and you're back in business.
- Leaking tank or faulty valve. Pooling water around the unit or rust streaks on the side. A tank leak needs replacement. A valve leak can often be repaired.
- Closed shutoff valve or frozen pipe. Someone closed the valve during maintenance and forgot to reopen it. Or in winter, an exposed supply pipe freezes. Open the valve fully counterclockwise. Never use a flame to thaw a pipe.
Five checks before you call
- Check the breaker. Look for the "hot water" switch on your board. If it's tripped, reset it.
- Check the pilot light. For gas systems, open the panel and look for the flame. If it's out, relight it.
- Check the shutoff valve. The handle should be parallel to the pipe. If it's crosswise, turn it.
- Listen for noises. Rumbling or popping means sediment. Time for a flush.
- Check for leaks. Any pooling water or rust streaks means you need an emergency plumber.
Northern Beaches reality check
Salt spray in Manly, Dee Why, and Brookvale corrodes exposed gas flues and electric element terminals faster than inland. Outdoor units in these suburbs need replacing 2-3 years sooner than the same model in Forestville.
Older homes in Mosman and Cremorne often have original hot water systems from the 90s tucked away in internal cupboards. Protected from salt but undersized for modern household demand, with decades of sediment buildup. If your system's original and the house was built before 2000, it's living on borrowed time.
Frequently asked questions
Why is my hot water not working but cold water is fine?
This means the problem is with your hot water system itself. A failed heating element, tripped breaker, extinguished pilot light, or sediment buildup. Cold water bypasses the heater entirely, so it flows normally while the hot side suffers.
How do I reset my hot water system?
For electric systems, locate the circuit breaker labelled "hot water" and reset it. Some electric tanks also have a thermostat reset button behind a small access panel. For gas systems, relight the pilot light following the manufacturer instructions. If you cannot find the panel or are unsure, call a plumber.
How long does a hot water system last?
Electric storage tanks last 8-12 years. Gas storage units last 8-10 years. Continuous-flow gas units last 12-15 years. Heat pump systems last 10-15 years. If your system is over 10 years old and has stopped working, replacement is more cost-effective than repair.
Can I fix a hot water system myself?
Basic checks like resetting a breaker, relighting a pilot, or checking a shutoff valve are safe DIY steps. Anything involving electrical components, gas lines, or internal tank repairs needs a licensed plumber or gas fitter. Faulty DIY repairs can cause serious injury or property damage.
Still no hot water? Give us a call.
Same-day repair across the Northern Beaches. Most fixes are under an hour. I'll tell you the price before I start.
Related reading
- Gas vs Electric Hot Water: Which Is Right for You?Compare running costs and choose the best system for your home.
- Signs You Need Emergency Plumbing ServicesNo hot water is a common emergency. Know when to call.
- Why Is My Hot Water System Leaking?Read this if you found water around your heater.
- How Long Should a Hot Water System Last?Know when replacement is more cost-effective.
- Hot Water System Maintenance ChecklistPrevent failures with regular servicing.