Leaking Hot Water System: What to Do Right Now
Isolate the water and the power or gas, and keep clear of the relief valve.
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THE SHORT ANSWER
In short
Close the cold water isolation valve on the pipe going into the unit. For an electric system, switch its circuit off at the switchboard if you can do it safely and dry; for gas, turn the gas off at the unit. Keep clear of a hot, hissing or steaming relief valve. Then call us: a small drip from the relief valve can be normal, but a puddle under the tank usually is not.
DO THIS FIRST
Do this first
1
Close the cold water valve
On the cold pipe going into the unit: turn it clockwise.
2
Power or gas off
Electric: its circuit at the switchboard, only if dry and safe. Gas: the gas valve at the unit.
4
Contain it
A bucket or towels; keep the water away from electrics.
5
Call us
0420 102 394, any hour.
SOURCES
Where this advice comes from
WHAT IS HAPPENING
Where the water is coming from changes everything
A hot water system can leak from several places, and they mean very different things. The temperature and pressure relief valve near the top is designed to let out a little water as the tank heats and the water expands: that is normal. Water dripping from fittings and valves on the pipes around the unit is usually repairable. Water coming from the bottom of the tank, or seeping out through the outer jacket, usually means the inner tank has rusted through, and a tank cannot be repaired.
Most storage tanks are protected from rust by a sacrificial anode: a metal rod inside that corrodes so the tank doesn’t. When the anode is used up, the tank itself starts to corrode, which is why tanks that are never serviced often fail from the bottom, and often without much warning.
A leaking hot water system is also a scald risk. Stored water must be kept at 60°C or more (NCC 2022, NSW), so a spraying valve or split fitting can release water hot enough to burn. Keep children and pets well back.
IS IT URGENT?
How serious is it?
| What you can see | How urgent | What to do |
|---|---|---|
| Water pouring from the bottom of the tank or through the jacket | Emergency: call now | Cold valve off, power or gas off, call us |
| Relief valve spraying, steaming or running constantly | Emergency: call now | Keep clear; turn the power or gas off at the unit if you can do so safely |
| A leak at a pipe fitting or valve, with the water off and the leak contained | Urgent: today | Bucket underneath, and book us for today |
| No hot water as well, with a baby, an elderly or unwell person at home | Urgent: same day | Call us: a failed hot water service is an urgent repair in a rental |
| The relief valve drips a little while the tank heats | Usually normal | Rheem says about 1/50 of the hot water used; more than a bucketful in 24 hours needs a check |
DO NOT
Don’t make it worse
- Don’t open the relief valve lever to "test" a leaking unit
- Don’t touch the unit or switchboard if you are standing in water
- Don’t keep heating a tank that is leaking from the bottom
- Don’t cap, plug or tie up a dripping relief valve. It is a safety device that stops the tank building up dangerous pressure.
- Don’t drain the tank yourself to stop the leak: it is full of very hot water, and an electric element can burn out if the power comes back on with the tank empty.
WHY IT HAPPENED
Why hot water systems leak
We have completed 122 hot water repair jobs since 2019, among 1,125 hot water jobs of every kind. Where our plumbers recorded a cause on repairs, the most common were: faulty tempering valve (33 jobs), faulty hot water element or thermostat (15 jobs), water leak (13 jobs), faulty pressure relief valve (9 jobs), burst water pipe (9 jobs).
| Likely cause | Tell-tale signs | The usual fix |
|---|---|---|
| Rusted-through tank | Water from the base, rusty water at the hot taps, an older system | Replace the system, often the same day |
| Faulty relief valve | A steady flow from the valve drain, even when the tank isn’t heating | Replace the valve |
| Faulty tempering valve | A leak at the valve near the unit, or water too hot or not hot enough at the taps | Replace the tempering valve |
| Leaking fitting or pipe | Drips at unions, the isolation valve or the pipes around the unit | Remake or replace the fitting |
| High water pressure | The relief valve discharges a lot, pipes bang | A pressure check, and a pressure limiting valve if it is needed |
WHEN WE ARRIVE
What we do when we get there
1
Isolate safely
Water, power or gas confirmed off at the unit, and the area around it made safe.
2
Find the leak point
Valve, fitting or tank: we show you which, because it decides between repair and replacement.
3
Fixed price first
For a repair or a new system, you approve the price before we start.
4
Repair or replace
Valves and fittings repaired on the spot where we can; a split tank means a new system, often the same day.
5
Check before we go
Temperatures and valves checked with the system running again.
WHAT IT COSTS
What a leaking hot water system costs to fix
Half of our 107 priced hot water repair jobs since 2019 cost between $498 and $2,915, including GST, with a median of $1,210.
The range is wide because it runs from a single valve to a major part. If the tank itself is leaking, see hot water replacement for the system types and what they cost.
$0 call-out Monday to Friday, 7:00am to 5:00pm. After hours a call-out fee of $199 to $399 applies, confirmed by text before we dispatch.
WHO IS RESPONSIBLE
Who is responsible?
A failure of the hot water service is on the NSW urgent repairs list, so in a rental the landlord arranges and pays for the repair (tenants: what to do).
In strata, a hot water system serving only your lot is usually yours; a central plant serving the building is the owners corporation’s (strata: who pays). In a business, check your lease: many make the tenant maintain landlord-supplied hot water units (commercial).
INSURANCE
Hot water leaks and insurance
Policies generally won’t pay for a hot water system that failed from age or corrosion. Water damage from a sudden failure of the tank may be covered as escape of liquid.
Before anything is removed, photograph the tank, the leak, the damage and the compliance plate on the unit, which shows its details and age. How to make a claim
NEXT TIME
Prevent it next time
- Have the relief valve checked when the system is serviced
- Know where the cold isolation valve is
- Most systems last about 8 to 10 years: plan the replacement before it fails
- Ask about the anode at each service: replacing it before it is used up can extend a tank’s life
- Keep the area around the unit clear and dry, so a new leak is easy to spot
QUESTIONS
Leaking hot water questions
WHAT TO DO RIGHT NOW
Other plumbing emergencies
MORE HELP
Emergency help
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