Hot Water Unit Leaking: What to Do Before the Plumber Arrives

A leaking hot water unit is one of those problems that gets dramatically worse the longer you ignore it. A drip can become a flood, a tank can rupture, and the unit itself can fail catastrophically if it runs dry while still energised. Here is exactly what to do in the 30 minutes between spotting a leak and the plumber arriving.

First: identify what kind of leak

There are four common leaks on a hot water unit, and they need different responses.

A drip from the temperature and pressure relief (TPR) valve, especially during heating cycles, is often normal - the valve is doing its job. If it is dripping constantly, the valve is failing or pressure is too high.

A leak from the cold water inlet or hot water outlet pipework usually means a connection has loosened or corroded.

A leak from the body of the tank itself (water pooling underneath, with no visible source above) means the tank is corroded and the unit needs replacement, not repair.

A leak from a gas connection on a gas storage or continuous flow unit is potentially dangerous - gas plus water is a combination only a gas-fitting licensed plumber should touch.

What to do in the first 5 minutes

Turn off the cold water isolation valve at the unit (usually a lever on the cold water line into the unit). This stops new water entering the tank.

Switch off the unit. Electric: flip the labelled isolation switch on the wall. Gas: turn the gas valve at the appliance to the off position. This prevents the unit from continuing to heat water it does not have.

If water is pooling on a tiled surface or coming inside, throw down towels and move anything water-sensitive out of the area.

Next 10 minutes: contain and document

Photograph the unit, the leak point, and any water damage. Note the make and model (usually on a sticker on the unit body) and the install date if visible. This makes the plumber’s visit faster.

If the leak is significant, put a bucket under the worst drip and check it every 15 minutes.

Next 15 minutes: book the plumber

Call a licensed plumber. In Victoria, hot water work is licensed under the Plumbing Regulations 2018 - only a plumber registered with the VBA (vba.vic.gov.au) can legally repair or replace the unit and issue the Certificate of Compliance. Newton Plumbing attends emergency hot water service across Melbourne’s east.

Is my unit repairable or do I need a new one?

A leaking TPR valve, faulty thermostat, or failed element on an electric unit is repairable, usually for $250-$600. A leaking tank body is not - the inner cylinder is corroded and replacement is the only safe option. The Energy Safe Victoria guidance (esv.vic.gov.au) is clear: a corroded tank is a failure risk.

FAQ

Is a few drips from the TPR valve normal?

A small amount during heating cycles, yes. Continuous dripping, no.

Can I use a leaking unit until the plumber arrives?

If the leak is minor and the unit can be isolated, yes. If the leak is from the body of the tank, switch it off and do not use it.

Is hot water replacement covered by insurance?

The damage caused by a sudden failure usually is. The unit itself is not - that is wear and tear.

Does Newton Plumbing carry replacement units on the van?

We stock the most common Rinnai, Rheem, and Reclaim units for same-day swap-outs in Melbourne’s east.

Phone Newton Plumbing - +61 414 951 362. Licence #107733.

Internal links: hot water Burwood, hot water Box Hill, hot water Blackburn, hot water Glen Waverley.

External links: vba.vic.gov.au, esv.vic.gov.au, standards.org.au, energy.vic.gov.au.