How to Quote a Hot Water System Replacement
A hot water swap looks like a like-for-like job until you're up a roof cavity converting electric to gas. Here's how to quote a hot water system replacement so access, valves and disposal don't eat your margin.
Not every hot water job is a simple swap. Replacing an accessible electric storage unit with the same thing is quick; upgrading to a heat pump in a tight roof space, or converting from electric to gas, is a different job entirely. The traps are the parts nobody sees on a walk-past — access, corroded pipework, an undersized circuit, and a pile of mandatory valves. This guide covers what to price and where the margin leaks.
What drives the price
Before you quote a figure, work out which job you're actually looking at. A like-for-like replacement in an easy spot and a full system change in a hard one sit at opposite ends of the price range. Scout the site for the things that turn a swap into a project:
- System change — going electric to gas, or storage to heat pump, means new services, not just a new unit.
- Access — underfloor, roof-cavity or tight-cupboard installs add hours and sometimes a second pair of hands.
- Corroded or undersized pipework — old copper that has to be re-run adds labour and materials fast.
- Electrical — heat pumps and larger electric units often need a circuit upgrade before they'll run.
- Relocation — moving the unit at all means re-running water, gas or power to the new position.
System types and what the unit costs
The unit itself is only part of the price, but it sets the baseline. These are typical supply-only figures for 2026 — confirm current pricing with Reece or Tradelink on the day, because unit costs move seasonally.
| System type | Unit cost | Best for |
|---|---|---|
| Electric storage | $600–$1,500 | Cheapest upfront; least efficient to run |
| Gas (instant or storage) | $800–$2,000 | On-demand hot water; add gas line if converting |
| Heat pump | $2,500–$4,500 | Highest upfront, lowest running cost |
Heat pumps cost more up front but can cut hot water running costs by around 70%, and state schemes like the Victorian Energy Upgrades and NSW Energy Savings Scheme offer rebates that close the gap. Point customers to the official state program for current eligibility — it often turns a dearer heat pump into the easier sell.
Working out labour
Labour is where the site conditions show up in the price. A like-for-like swap in an accessible spot runs about 3–4 hours — isolate, drain, remove, install, test and commission. A system change or an awkward install is a different number.
- Like-for-like, easy access — roughly 3–4 hours end to end.
- Electric-to-gas or heat pump — 6–8 hours or more, with new services and electrical.
- Difficult access — underfloor or roof-cavity work adds hours on its own.
- Pipework changes — re-running copper or switching to PEX adds time and material.
Most plumbers charge $80–$120/hour, so getting the hours right — plus travel and any site induction — matters more than the unit price on most jobs.
Certificates, disposal and the small materials
The bits that don't fit on the unit invoice are the bits most often left off the quote. They're not optional, and together they add up.
- Compliance certificate — a licensed plumber must certify regulated work, and the certificate carries a fee.
- Old-unit disposal — $50–$150 depending on size and your local waste facility.
- Mandatory valves — a pressure limiting valve (AS 1357.2) and tempering valve (AS 4032.2) on every job.
- Consumables — pipe lagging, extra copper or PEX, fittings and electrical cable.
Underquote these 'minor' items and you can quietly lose $200–$400 on a standard job.
Common traps that turn profit into loss
- Assuming every job is a swap. Quote the job in front of you, not the last one. A heat pump in a roof cavity is not the same job as a like-for-like electric swap, and pricing it that way is a straight loss.
- Skipping the site inspection. Asbestos lining on old pipes, a rotten subfloor from years of leaks, or an undersized circuit — none of it shows up over the phone. Inspect before you price.
- Forgetting the valves and offcuts. New GPOs, mounting brackets, drainage and the compliant valves all add up. Left off the quote, they come straight out of your margin.
- Underestimating disposal and access. Getting the old unit out of a tight space and to the tip takes real time. Price it, don't wave it away.
- Quoting on stale prices. Unit and material costs shift seasonally. Verify current supplier pricing before the quote goes out, especially on the unit itself.
Pro tips for a hot water quote that holds
- Do a proper site inspection before every replacement — access and pipework decide the price.
- Confirm the existing circuit can handle a heat pump before you promise one.
- List the compliant pressure limiting and tempering valves as their own line items.
- Include old-unit disposal so the tip run isn't a cost you swallow.
- Build in a 5–10% contingency on older properties for what you can't see yet.
- Educate the customer on running costs and rebates to justify the more efficient system.
ServiceYak keeps your unit prices, valves, labour rate and disposal fee in a reusable kit, so a hot water quote comes together on site — itemised, compliant, and sent as a PDF before you pack up.
Frequently asked questions
How much does it cost to replace a hot water system in Australia?
Installed, most replacements land between $1,500 and $3,500. A like-for-like electric or gas swap sits at the lower end; a heat pump or an electric-to-gas conversion, with new services and electrical, sits at the top.
How long does a hot water system replacement take?
A straightforward like-for-like swap in an accessible spot is about 3–4 hours. A system change, difficult access, or pipework and electrical upgrades can push it to 6–8 hours or more.
Are there rebates for hot water systems?
Often, for efficient systems. State schemes like the Victorian Energy Upgrades and NSW Energy Savings Scheme subsidise heat pumps and solar hot water. Eligibility varies by state and council, so send customers to the official program to check current offers.