What it costs to install a reverse osmosis system in Australia

The system is the easy part of the budget. A WaterMark-listed system starts at $499 at Bunnings (the Philips 75 GPD station, checked 21 October 2026). Cheaper five-stage kits on Amazon AU aren’t on the WaterMark register, so a licensed plumber can’t install them. What people forget is that an under-sink reverse osmosis system is plumbing, with a drain connection, a new tap and often a hole in the benchtop. Here is what that part costs, with the sources named.

The sourced numbers

We do not guess at trade prices. These are the published figures we could find on 4 October 2026.

Source	What it says	Figure
hipages cost guide (updated 24 July 2026)	Plumber hourly rate, national range	$80 to $200 an hour
hipages	Call-out fee, business hours	$60 to $250
hipages	Fit or replace bath or basin taps	$80 to $350
hipages	Basin, sink or toilet installation	$250 to $600
Bunnings In Home Services	Water filter installation, tap only	$226.60 fixed

An under-sink RO install sits between hipages’ tap job and its sink job: more than a tap swap because of the drain and the tee into the cold line, less than a sink. Call it one and a half to three hours of labour plus the call-out, which lands at roughly $230 to $600 in most cities. Bunnings’ fixed $226.60 is the floor for the simplest case.

What pushes the price up

No tap hole. Most RO systems come with their own small tap, which needs a hole in the benchtop or sink. Drilling laminate or stainless steel is quick. Drilling stone, which many Australian kitchens now have, is a specialist job with a diamond core bit, and plumbers either charge extra or send you to a stonemason. Ask before the plumber arrives. The alternative is a three-way mixer that replaces your existing tap and uses the existing hole; Stefani sells one at Bunnings for $249, which is more than the plumber would charge to drill laminate but less than a stonemason.

No power point. Tank systems run on mains pressure and need no electricity. Tankless systems (Philips 400 GPD, Waterdrop X8) have a pump. If your under-sink cupboard has no power point, an electrician has to add one, and that is a separate trade and a separate bill.

A long drain run. The drain saddle clamps onto the sink waste. If the sink waste is on the other side of a dishwasher or the system has to sit in a different cupboard, the plumber runs tube and charges for the time.

Low or high mains pressure. Tank RO systems want at least 40 psi (about 280 kPa) at the inlet. Houses with very low pressure need a booster pump; houses above 500 kPa need a pressure limiting valve, which many already have at the meter. Both are extra parts.

Certification. WaterMark’s own consumer page says a licensed plumber isn’t permitted to install a water filter that isn’t WaterMark-certified. Of the systems we have priced, the two Philips stations, the Stefani and the Waterdrop X8 are on the WaterMark register; the Geekpure and iSpring kits sold on Amazon AU aren’t (checked 21 October 2026). Look your system up in the WaterMark product database before you buy, not when the plumber is on the clock.

The all-in budget

Scenario	System	Install	Total
Laminate bench, existing tap hole, tank system	Philips 75 GPD, $499	$226.60 to about $450	$726 to $949
Same kitchen, WaterMark system from Bunnings	Stefani, $625	$226.60 to about $450	$850 to $1,075
Stone bench, tankless, no power point	Philips 400 GPD, $699	$300 to $600 plumber, plus stonemason and electrician	$1,200 and up
Rental or no budget for trades	Waterdrop C1S countertop	$0	Check price

The right-hand column is the number to compare against a jug or an under-sink carbon filter. For a Melbourne or Sydney household that wants chlorine taste gone, the comparison is not close: a carbon under-sink filter installs for the same labour and the system costs a third as much. For Adelaide or Perth, or anyone removing fluoride, the extra is what the result costs. Our worth-it guide goes through that decision.

What a good install looks like

Ask the plumber for these and you will get a system that lasts.

• An isolation valve on the feed tee, so you can change cartridges without turning off the kitchen.
• The drain saddle above the trap, on the sink side, so sewer gas cannot reach the system.
• Tubing clipped, not left in a tangle behind the bin.
• The tank pre-charged to the pressure in the manual (usually 5 to 7 psi empty).
• The first two tanks flushed to waste before you drink, which the manual will say and the plumber may skip.
• A sticker inside the cupboard door with the install date and cartridge schedule.

Running costs after the install

Pre-filters every six to twelve months, the membrane every two to three years, the post-carbon yearly. Budget $80 to $200 a year depending on the brand, and buy a $20 TDS meter so you change the membrane when the reading climbs rather than on a guess. The cartridges guide covers sizes and prices.

The competition

We checked these on 21 October 2026.

• Geekpure 5-stage (Amazon Australia). The cheapest complete kit we found, with quick-connect fittings, but it isn’t on the WaterMark register, so a licensed plumber can’t install it.
• iSpring RCC7AK and RCS5T (Amazon Australia). A tank kit with a remineraliser and a tankless unit; neither is WaterMark-listed.

The one trap

Letting the plumber’s quote decide the system. A tradesperson who turns up with a system they stock has one install price in mind and will fit what is on the van. Buy the system first, having checked it is on the WaterMark register, then book the plumber for a fit-only job and tell them exactly what they are connecting: tee, drain saddle, tap, and whether there is power. The quote will be lower and the system will be the one you chose. The full list of systems is in the reverse osmosis guide.