Written by David MacKenzie, 13 March, 2026
If you have absolutely no hot water, the culprit is most likely a tripped circuit breaker (for electric systems) or a blown-out pilot light (for gas). If your water is running lukewarm or running out too fast, the issue is usually a faulty tempering valve or sediment buildup at the bottom of the tank.
Nothing ruins a morning faster than a freezing shower, especially during a Melbourne winter cold snap. If you’ve turned the tap and found no hot water (or just lukewarm water), you aren’t alone. Across Melbourne, hot water systems work hard against fluctuating weather and aging infrastructure. Before you panic, check out this checklist put together by David MacKenzie, expert hot water plumber and owner of Pakenham-based DMACK Plumbing.
We’ll look at the common hot water system issues we see on a daily basis and how to deal with them. You might save yourself a service call, or at least know exactly what to tell your plumber.
Scenario 1: There is No Hot Water at All
If the water is completely cold, the heating source has failed or been cut off.
Check Your Circuit Breaker (Electric Systems)
Did you know that 13% of electric hot water failures are simply tripped circuit breakers?
- The Fix: Check your switchboard for a switch labelled “Hot Water” or “HWS.”
- If it’s off: Flick it back on. If it trips again immediately, you likely have a blown fuse or a dead heating element.
- If it’s on: The issue is internal, likely a thermostat or element failure requiring a professional plumber.
Check the Pilot Light (Gas Systems)
For gas units, strong winds can sometimes extinguish the pilot light. Check if the flame is visible.
- The Fix: Try to relight it according to the manufacturer’s instructions.
- The Catch: If it won’t relight or stay lit, the thermocouple (a safety sensor) may have failed. This shuts off the gas supply to prevent leaks and requires replacement.
Safety Note: If you smell gas, turn the unit off immediately. Energy Safe Victoria recommends servicing gas appliances every two years to prevent carbon monoxide leaks, which can be caused by blocked flues or faulty burners.
Scenario 2: Water is Lukewarm or Runs Out Too Fast
This is the most common complaint we hear from local families: “The water starts hot but goes cold after 5 minutes.”
The Sediment Factor
While Melbourne generally has good water quality, older systems and specific areas still suffer from mineral buildup. Over time, sediment settles at the bottom of your tank.
- The Stat: Our data suggests up to 60% of tank efficiency issues are accelerated by sediment buildup.
- The Result: That layer of sludge takes up space. A 135L tank might effectively only be holding 100L of water because the bottom is full of sediment (a problem found in 19% of serviced systems).
Is Your Tempering Valve Faulty?
By law, your water is heated to over 60°C to kill bacteria, but delivered to taps at 50°C via a tempering valve. If this valve fails, it might be mixing in too much cold water, leaving you with a tepid shower even if the tank is boiling hot.
Scenario 3: Leaks and Drips
Pressure Relief vs. Tank Corrosion
- Normal: A little water dripping from the relief valve (PTR valve) is normal as the tank heats up.
- Not Normal: Heavy flows or water leaking from the bottom of the cylinder. This usually indicates the steel tank has rusted through—often due to a sacrificial anode that wasn’t replaced.
Need a Hot Water Plumber?
If you’ve checked the breaker and the pilot light but still have no hot water, don’t risk a DIY fix on high-voltage or gas appliances.
Need hot water sorted fast? Dmack Plumbing offers reliable, emergency hot water repairs across Melbourne. Whether it’s a quick element replacement or a tank flush to clear sediment, we get your water running hot again without the upsell.
Contact Dmack Plumbing today for a rapid response.
