DIY or licensed installer? The honest version.
We are not going to pretend a hot water swap is rocket science - it is four connections and a bit of lifting. The reason you cannot legally do it in Victoria has nothing to do with difficulty and everything to do with the three things that go wrong quietly: temperature, pressure and gas. Here is what you can do yourself, and where the line sits.
What you can do, and what you cannot.
Yours to do, no licence needed.
- Lift the PTR valve lever for a couple of seconds once a year to flush debris off the seat. Stand clear - what comes out is 60 degrees.
- Relight a gas pilot following the printed instructions on the unit itself.
- Check and reset the isolating switch or circuit breaker at the switchboard.
- Clear vegetation, stacked boxes and garden beds away from an external unit so the base stays dry and the flue stays clear.
- Read the compliance plate and send us the model and manufacture date. That one photo often saves a call-out.
Licensed work, full stop.
- Connecting, disconnecting or altering any heated water service - that is the wording in the Plumbing Regulations 2018.
- Elements, thermostats, anode rods, tempering valves, PTR valve replacement.
- Anything touching gas, which needs a Type A gasfitter specifically under Energy Safe Victoria, not just a plumber.
- Capping a gas line when converting to electric - and that generates its own decommissioning record.
- The dedicated circuit for a heat-pump, which is an A-grade electrician's job.
There is no homeowner exemption for hot water in Victoria. Tap washers, yes. Heated water services, no. It does not matter that you bought the unit, that you are a competent tradesperson in another field, or that the old one lifted off the stand easily.
The four faults we find on unlicensed installs.
We get called to these after the fact - usually when the house is being sold, or when something has already let go. Every one of them made hot water perfectly well on day one, which is exactly the problem.
- No tempering valve. AS/NZS 3500.4 requires a storage cylinder to hold water at 60 degrees or above to suppress Legionella, while water delivered to bathroom outlets must be no hotter than 50 degrees, dropping to 45 degrees in aged-care, early-childhood and healthcare settings. A tempering valve is what reconciles those. Leave it out and the shower runs at 60 degrees, which will scald a toddler in well under a second.
- PTR discharge piped wrong. The pressure and temperature relief valve is the only thing standing between a corroded cylinder and a pressure vessel. Its discharge line has to run continuously downhill to a safe visible point. We have found them piped uphill, capped, and once run into a stormwater pit where nobody would ever see it dripping.
- Inadequate base or unrestrained stand. A 250L storage unit weighs over 300kg full. It needs a proper base, and a stand needs restraint. Second-hand stands cut down to fit are a recurring theme.
- Gas connections tested by feel. A Type A gasfitter pressure-tests a gas connection with a manometer and documents it. A soapy-water squirt is not a test, and a slow leak behind an external unit is not something you smell from the kitchen.
None of these are about gatekeeping trade work. They are the four things that kill or maim, and they are the reason the certificate exists.
The compliance certificate is the whole point.
Under the Plumbing Regulations 2018, a licensed plumber must issue a compliance certificate for plumbing work valued over $750, and it is lodged with the Victorian Building Authority. That document is not bureaucracy for its own sake - it is the only proof that exists that your hot water system was installed by someone accountable. You will want it at sale, at insurance claim time, and any time future gas work is done on the property. We walk through exactly what that document is, and the gas decommissioning record that goes with it, on our hot water compliance certificate page.
A straight replacement in the same position does not need a building permit under the Building Regulations 2018, so the certificate is the entire paperwork trail. Relocating a unit or a heat-pump compressor does not normally need a permit either, but does need a registered plumber to sign off that the new position meets AS 3500.4 clearance and venting requirements.
Before you book anyone - us or otherwise - check the licence number on the VBA public register at vba.vic.gov.au. It takes 30 seconds. If a quote does not carry a licence number, that tells you everything. Our number is on every quote, and the trades we coordinate with on heat-pump circuits and solar roof work are listed on our local trades page.
What the licensed version actually costs, with a worked example.
This is the part most DIY reasoning gets wrong: the labour component of a hot water job is smaller than people assume, because most of the money is the unit itself. Current South East Melbourne ranges: diagnostic call-out $90 - $150, element $220 - $420, thermostat $180 - $320, anode rod $220 - $380, tempering valve $220 - $380, PTR valve $180 - $280, electric storage replacement $1,500 - $2,400, gas storage replacement $1,800 - $2,800, gas instantaneous $1,900 - $3,200.
A worked example - Cranbourne, owner-supplied electric unit.
Owner bought a 250L electric storage unit online for $1,150 and asked what we would charge to fit it. Our answer: $620 labour, including removal and disposal of the old unit, a new tempering valve, PTR valve, flexible connections and the compliance certificate lodged with the VBA. Total to the owner $1,770.
Our supply-and-install price for the same job with a unit we source: $1,950. So the owner saved $180 - about 9 percent - and in exchange took on the unit warranty themselves. Six years later, if that cylinder fails, they chase the manufacturer with their own online receipt while we would have handled it. That is a fair trade if you go in with eyes open, and we are happy either way. What is not a fair trade is saving the $620 by doing it yourself: you keep the $620 and lose the certificate, the tempering valve, the correct PTR discharge, and your insurer's goodwill. That last one is not abstract - an unlicensed install is one of the few things that will get a burst hot water claim declined outright. See the pricing guide for the full 2026 table.
One caveat on supply-your-own: it does not work for heat-pumps. Both the Solar Victoria rebate and the STC scheme require the accredited installer to supply and install the approved product, so buying the unit yourself forfeits $1,700 to $2,100 of rebate to save a few hundred on the box. The detail is on our heat-pump hot water page.
The questions people ask before they pick up a spanner.
Is it legal to install your own hot water system in Victoria?
No. Connecting, disconnecting or altering a heated water service is licensed plumbing work under the Plumbing Regulations 2018, and it must be carried out by a plumber licensed or registered with the Victorian Building Authority. Anything touching gas additionally requires a Type A gasfitter under Energy Safe Victoria. It does not matter that you bought the unit yourself, that you are a competent tradesperson in another field, or that the old one came out easily. There is no homeowner exemption for hot water in Victoria, unlike changing a tap washer, which you are welcome to do.
What can I legally do myself on a hot water system?
A short but genuinely useful list. You can lift the PTR valve lever for a couple of seconds once a year to flush debris off the seat. You can relight a gas pilot following the instructions on the unit. You can check and reset the isolating switch or circuit breaker at the switchboard. You can clear vegetation and stacked boxes away from the unit so the base stays dry and the flue stays clear. You can read the compliance plate and tell us the model and manufacture date. Everything past that - elements, thermostats, anodes, valves, connections - is licensed work.
What actually goes wrong when a hot water system is installed unlicensed?
The four we see most: no tempering valve, so bathroom outlets deliver scalding water in breach of AS/NZS 3500.4; PTR discharge piped somewhere it should not go, so the tank's only pressure protection cannot vent safely; the tank sat on an inadequate base or an unrestrained stand, which is a serious problem for a 250L unit weighing over 300kg full; and gas connections tested by feel rather than by manometer. None of those stop the unit making hot water on day one. All of them are why the rules exist.
Will my insurance still pay out if the hot water system was installed by an unlicensed person?
Assume not. Home insurance policies generally exclude loss arising from work that was required to be done by a licensed tradesperson and was not. When a tank lets go and floods a hallway, the assessor's first question is who installed it and where the compliance certificate is. No certificate means no evidence the work was compliant, and that is the gap the exclusion sits in. You are also personally exposed if a scald or a gas incident injures someone. The saving on unlicensed labour is a few hundred dollars; the exposure is the house.
Can I supply my own hot water unit and just pay you to install it?
Yes, we will fit a unit you have bought, and our workmanship warranty still applies to the installation. What changes is that the unit warranty becomes yours to manage - if the cylinder fails in year six you are dealing with the manufacturer directly rather than us handling it. You also lose the rebate path on heat-pumps, because Solar Victoria and the STC scheme both require the approved installer to supply and install the approved product. In practice, supply-your-own saves less than people expect and costs more when something goes wrong.
Licensed hot water across the City of Casey and the South East.
Licensed, certified, and cheaper than you think.
VBA-licensed plumber and Type A gasfitter on every job. Compliance certificate lodged and emailed to you.