What has changed lately?
A new meter, a change of retailer or tariff, or a power outage can change when an off-peak hot water circuit is switched on. If the tank now heats for only part of the night, it may not be full by morning. A new household member, longer showers, a higher-flow shower head or a new appliance plumbed to hot all add up as well.
Winter matters too. The water coming into the tank is colder in July, so each shower mixes in more hot water to reach the same temperature, and the tank takes longer to reheat. A system that was just big enough in summer can fall short on cold mornings.
Faults inside an electric tank
Electric storage tanks heat with an element controlled by a thermostat. When the thermostat drifts or fails, the water may sit cooler than it should and run out sooner. A failing element can heat slowly and often trips the safety switch as it leaks current to earth. Some tanks have two elements, and when one fails the tank keeps working with less hot water.
Sediment settles at the bottom of a tank over the years and takes up space, and a tempering valve that mixes in too much cold water can make hot water seem to run out. Valves and flushing are work for a licensed plumber. Elements, thermostats and the circuit are electrical work, which our team tests.
Heat pumps run out differently
A heat pump water heater recovers more slowly in cold air. If its timer allows only a short window on cold nights, or the heat pump side has stopped and the backup element is doing all the work, you'll notice shorter showers well before the water goes fully cold.
What you can safely do now
- Check the switchboard for a tripped hot water circuit breaker or safety switch, and reset it once.
- After a meter change, new tariff or power cut, ask your retailer what times the off-peak circuit now runs.
- Check the clock and timer on a heat pump unit after any power cut.
- Note whether the water is lukewarm all day or runs out after a few showers, as that narrows the fault.
Services that can help
Read more in our guides
Related questions
- My electric hot water has gone cold. What can I check?Start at the switchboard: look for a tripped hot water circuit breaker or safety switch and reset it once.
- What is the off-peak or timer switch on my switchboard?It controls an off-peak circuit, usually for electric storage hot water and sometimes for slab heating or a pool pump.
- Is it normal for my hot water system to drip from the valve?A little water from the relief valve drain while the tank is heating is normal, because water expands as it heats and the valve lets the extra out.
- Why does my hot water smell like rotten eggs?A rotten egg smell that comes only from the hot tap usually starts inside the storage tank.
Sources for this answer
1 source, with the date each was checked
- 1.Energy Safe Victoria: Locate your electricity box outside your home and check whether the safety switch has tripped. If it has tripped, reset the switch. If the switch won’t reset, call a licensed electrician. Accessed 30 September 2026.
General information for homes in Victoria. Every installation is different, so treat this as a starting point. Where this answer refers to Victorian safety or rental rules, the sources above have the current requirements.