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Should I Turn Off My Hot Water When on Holiday? An Honest Plumber's Answer
Should you turn off your hot water when you go on holiday? Here's a plain-English answer for Melbourne homes. Below we cover what works, what doesn't, and when to call a licensed plumber.
Quick answerFor trips over a week, turning OFF gas storage (or switching electric storage to "Vacation" mode, or off at the breaker) saves a small amount and is fine, but flush the unit thoroughly when you return before drinking the hot water. Continuous-flow units only run when you use water, so there's no benefit to turning them off. Heat pumps usually have a "Vacation" mode that's the right answer for trips of any length.
This is one of those questions where the answer depends on the system type AND how long you're away. Here's the practical breakdown.
Going away soon, or home to no hot water? Call Prime Plumbing & Gasfitting on 0475 407 670, Mon-Fri 7-5, Sat 8-1. See the suburbs we cover.
Going away over Christmas: what to do with your hot water
If you're away over Christmas, here's the short version of this page. Summer is also when the sun is at its strongest, which matters if you've got solar. The sections below explain the why.
- Check what you've got. Look at the unit and its label. Panels on the roof feeding a tank means solar. A fan unit on top of or beside the tank is a heat pump. A slim box on the wall with no tank is continuous flow. A tank with a gas line and a control knob is gas storage. A plain tank with neither is electric storage.
- Gas storage. Away under a week: leave it on. One to three weeks: your call, the saving is small. Three weeks or more: turn it off at the gas control knob, following the label on your unit. Closing the small gas isolation valve on the line into the unit is optional.
- Electric storage. Use Vacation or Holiday mode if the controller has one. If it doesn't, it comes down to your tariff. On a standard all-day tariff, switching it off at its circuit breaker for a week or more saves real money. On off-peak, leaving it on is fine for shorter trips. Turn it off at the breaker, never at the water valve.
- Heat pump. Switch the controller to Vacation mode. No vacation mode? Leave it on for trips under two weeks. For longer trips, switch it off at the circuit breaker and flush it when you get home.
- Solar. Leave the solar side alone. The panels rely on water moving through them to stop them overheating, and Christmas is peak sun in Melbourne. You can switch the electric or gas booster off while you're away, or use Holiday mode if the controller has one. Don't climb on the roof to cover the panels.
- Continuous flow. Leave it on. It only burns gas while a hot tap is running, so there's nothing to save. If it's an older unit and a leak while you're gone worries you, close the cold water and gas isolation valves at the unit.
- Water at the meter (optional). For trips of two weeks or more, especially in an older house, turning the water off at the meter protects you from a burst flexi hose or a leaking appliance. Turn a gas or electric storage tank off first (as above), turn the water off at the meter, then open a cold tap inside to take the pressure off. If you've got solar, leave the water on at the meter over summer, or ask a plumber about your system first. If someone is minding the house, leave it on.
- When you get home. Turn things back on in reverse: water at the meter, isolation valves, then relight the gas unit following the label (usually knob to PILOT to light it, then ON), or put the breaker back on, or take the controller out of Vacation mode. Give the tank time to get back to full temperature (an off-peak electric tank may not be hot until after its next overnight heat). Then run the hot water at every tap and shower for at least 5 minutes before you drink it, cook with it or shower in it. Stay out of the shower steam while it runs. If you've got solar, the tank can be very hot after a sunny fortnight with nobody using it. Run the kitchen and laundry taps carefully, mixing in cold, and keep kids away from them.
- When to call a plumber. Before you go, if the tank is already weeping, rusty around the base or the relief valve is running constantly, get it checked now rather than leave it with nobody home. After you get back, call if the pilot won't light or won't stay lit after following the label a couple of times, if there's water pooling under the unit, if an electric or heat pump unit is still cold the day after you switched it back on, or if the hot water is still discoloured after the flush. If you smell gas, don't relight anything: leave the house, then call your gas distributor or 000 (see gas leak signs).
Everything on this list is operating the unit, which any homeowner can do. Opening the unit up, replacing a valve or part, or touching the gas or water connections is licensed work in Victoria. If you're not sure where that line sits, read when you can do your own plumbing work.
By system type
Gas storage (Rinnai, Rheem, Vulcan, Bosch storage)
Trips under a week: leave it on.
Trips 1-3 weeks: optional, turning OFF saves maybe a few dollars on the gas bill. If you choose to turn off, flush thoroughly on return (run hot water for 5+ minutes at every outlet before using).
Trips 3+ weeks: turn off. You're getting actual savings AND avoiding running a hot tank you're not using. Same flush-on-return advice.
How to turn off a gas storage unit:
- Turn the gas control knob to PILOT (the pilot stays lit and the main burner stays off), or fully OFF if you'd rather, following the label on your unit
- Optionally close the gas isolation valve at the unit (small lever on the gas line)
- Optionally close the cold water isolation valve (lets the tank stay full but doesn't refill if there's a leak)
On return: turn the gas back to ON, follow the relight instructions on the unit's label, give the tank 30-60 minutes to come up to temperature, then flush hot water at every outlet for 5+ minutes before drinking or using for cooking.
Electric storage (Rheem Stellar, Rinnai HotFlo, Aquamax, Dux Proflo)
All trip lengths: switch to "Vacation" or "Holiday" mode if your unit has it (most modern units do, usually labelled on the controller).
If your unit doesn't have a vacation mode, the tariff matters:
- Off-peak (continuous tariff): leave on. Savings from turning off are minimal because you're paying off-peak rates anyway.
- Off-peak (overnight only): leave on for trips under a week. For longer, optionally switch off at the dedicated circuit breaker.
- Standard tariff (full-time on): turning off for trips of 1+ weeks saves real money on the electricity bill.
Important: don't turn off an electric storage unit at the isolation valve (water side), turn it off at the circuit breaker (electrical side). Leaving water in the tank is fine; leaving the heater running on an empty tank is not.
Continuous-flow gas (Rinnai Infinity, Rheem Metro, Bosch Highflow)
All trip lengths: leave it on. Continuous-flow units only consume gas WHEN water is flowing through them. With nobody home, water isn't flowing, so the unit isn't using gas (beyond a tiny pilot or electronic standby). Turning off just creates the inconvenience of relighting when you return, with effectively zero savings.
The exception: if you're concerned about a leak developing while away (legitimate concern on older units), close the cold water isolation valve and the gas isolation valve as a safety precaution. The unit doesn't need a "shut down", you're just isolating it from supply.
Heat pumps (Sanden, iStore, Reclaim Energy, Stiebel Eltron)
All trip lengths: switch to "Vacation" mode on the controller. Most modern heat pumps have this, it suspends scheduled heating cycles while keeping the tank at a low standby temperature.
For older heat pumps without vacation mode, leaving on is generally fine for trips under 2 weeks (heat pumps run efficiently and standby cost is low). For longer trips, switching off at the circuit breaker is OK, flush on return.
Solar hot water (panels + tank)
Don't turn off solar, even when you're not using hot water, the panels are designed to circulate water through the tank to prevent the panels themselves from overheating. Disabling the system can damage the panels in summer. Most solar systems have a "Holiday" mode on the controller that handles this correctly.
The legionella concern (why "off + flush" matters)
When hot water sits in a tank below ~50°C for days, Legionella bacteria can multiply. Australian regulation already requires tempering valves to limit OUTLET temperature to 50°C max, but the TANK should run at 60°C+ to keep bacteria suppressed.
If you turn the heater off entirely, the tank cools to ambient over a few days.
The fix is simple: when you return, run hot water for 5+ minutes at every outlet (especially showers) BEFORE breathing in the steam or using it for cooking/drinking. Once the tank is back up to full temperature, a five-minute hot flush clears the water that sat in the pipes while you were away.
The longer the off period, the more important the flush.
What about turning off the water entirely?
A different question. Some homeowners shut off the mains water valve at the meter before holidays, protects against burst pipes or appliance leaks while away.
This is a separate decision and applies regardless of hot water unit type. If you do shut off mains:
- Turn off a gas or electric storage hot water unit first. Leave solar and continuous flow units as they are, and if you have solar, leave the water on in summer or ask a plumber first
- Open one tap inside the house briefly to relieve pressure in the line
Worth doing for trips of 2+ weeks, especially in older homes where supply line failures are more likely.
What about the hot water unit's pilot? (gas storage only)
If you turn off a gas storage unit, the pilot also goes out. That's expected behaviour. On return, you relight the pilot following the instructions on the unit label.
If you're worried about whether YOU can relight it, leave a relit unit running while you're away, the cost is small. Or have someone (housesitter, neighbour with a key) check on it.
Book a service
Hot water issue or pre-holiday assessment? Call 0475 407 670 or send the make + model of your unit through the contact form.
- BPC #103414: licensed by the Building and Plumbing Commission
- Gasfitting: licensed by the Building and Plumbing Commission
- 4.9 stars on Google
- Fixed-price written quote before any work
- Certificate of Compliance lodged with the BPC on gas work
Related: How long does a hot water system last? · Is it dangerous if the pilot light goes out? · Hot Water Systems Melbourne · Hot Water Replacement Melbourne
About the author
Alister Williams is the founder and lead plumber of Prime Plumbing & Gasfitting. He's been licensed under BPC #103414 for over a decade, is licensed for gasfitting with the Building and Plumbing Commission, and is a member of the Master Plumbers Association of Victoria.
When to call us
Book a hot water service visit if:
- You don't know how old your unit is (we can decode the data plate and tell you)
- You're concerned about leaks while away on long trips
- You want to discuss replacing an aging unit before going overseas
- You've returned from a trip and the unit isn't relighting / restarting properly
Service area
Prime Plumbing & Gasfitting services hot water issues across Melbourne's eastern, south-eastern, inner-east and bayside suburbs. See all suburbs we service
When to Call a Licensed Plumber
Some plumbing problems are DIY-friendly; others need a licensed professional under Victorian law.
Anything involving gas, sewer drainage, hot water units, backflow prevention, or work behind tiled walls must be handled by a licensed plumber or gasfitter.
Frequently asked questions
Not directly. Leaks happen because of pre-existing wear, not because the unit is on. But IF a leak develops while you're away on a unit that's running, water will keep flowing, and that becomes a much bigger problem than a leak you discover after a 2-day weekend. For trips of 2+ weeks, isolating the cold water inlet to the hot water unit (or shutting off mains entirely) is reasonable insurance.
Not by turning the thermostat down. A storage tank needs to stay at 60°C or more to keep bacteria like legionella in check, and on many storage units the thermostat setting is meant to be changed by a licensed plumber, not the owner. The better options are Vacation or Holiday mode if your controller has one, or setting a gas storage unit to PILOT, which keeps the pilot lit with the main burner off. On continuous flow there's nothing to turn down, because the unit only fires when you use hot water.
You CAN close that, but it's a bigger commitment, you'll need to relight every gas appliance (hot water, oven, gas heater) on return. For trips of 4+ weeks where you're concerned about gas leaks while away, it's worth doing. For shorter trips, the unit-level isolation valve is enough.
Yes if you can isolate the irrigation separately. Turning off mains entirely will also disable irrigation, your garden suffers. Most properties have an irrigation isolation valve that lets you keep irrigation running while shutting off house supply.
Run hot water for 5 minutes at every outlet before using normally. The flush retroactively suffices.
Some modern systems (heat pumps especially) have phone apps that let you switch to vacation mode remotely. For older units, a simple switch on the circuit breaker (electric) or the gas control (gas) is the only option.
Start with whatever you turned off. On gas storage, check the gas isolation valve on the line is open, then relight the pilot following the label on the unit (usually knob to PILOT, light it, hold, then turn to ON). On electric storage and heat pumps, check the hot water breaker is on and the controller is out of Vacation mode, then give it time. On an off-peak tariff it can stay cold until it has had its overnight heating run. On continuous flow, check the isolation valves are open and the unit's power point is switched on. If you closed the water at the meter, make sure it's fully open again. If the pilot refuses to light, or goes out again soon after, stop there and call a licensed gasfitter, and if you smell gas, don't try to relight it at all. Our no hot water troubleshooting guide covers the other causes.
Before You Book
A quick checklist to share with your plumber when you book:
- When did the issue start?
- Is it isolated to one fixture or multiple areas?
- Are there any visible leaks, smells or unusual sounds?
- Have you turned off the relevant isolation valve?
If you're unsure, Prime Plumbing & Gasfitting can inspect the issue and explain the options before any work starts. Call 0475 407 670 or request a quote online.
Need someone to look at your hot water? Call Prime Plumbing & Gasfitting on 0475 407 670. We're open Mon-Fri 7-5, Sat 8-1. Have the make and model from the unit's label handy when you ring, and let us know what type of system it is and what it's doing. Check your suburb on our service area page.
