Three stars is the floor. Under state and territory plumbing regulations, toilets installed in new residential housing and in renovations need to meet a minimum water efficiency, and for toilets that minimum is at least three stars, which is a six litre full flush and three litre half flush dual flush suite. Four stars is the rating most Australian households should actually aim for, because the step from three to four stars is the largest single water saving available on the scale and it costs you nothing in daily use. Some jurisdictions and some water-restricted areas require better than three stars, so confirm the requirement for your address with your plumber or certifier before you buy.
That is the short answer. The rest of this guide explains what the star rating actually measures, what the rules are in New South Wales, why WELS and WaterMark are two different things that both matter, and how to check a toilet is genuinely registered before you pay for it.
What is the WELS scheme?
WELS stands for Water Efficiency Labelling and Standards. It is a mandatory Australian Government scheme, established under the Water Efficiency Labelling and Standards Act 2005 and administered by the Department of Climate Change, Energy, the Environment and Water. It covers washing machines, dishwashers, showers, toilet suites, urinals, taps and flow controllers.
Products under the scheme are tested in an accredited laboratory, registered, and given a star rating of up to six stars along with a figure for how much water they use. That is what the blue and white water rating label on the product or the packaging is showing you. Product testing, rating and labelling requirements sit in Australian and New Zealand Standard AS 6400:2016 Water efficient products, rating and labelling.
It is unlawful to supply a WELS-regulated product that is not registered and labelled. Retailers, including online stores selling into Australia, are required to display the water efficiency details of the regulated products they sell. If a toilet suite has no water rating label and no registration number anywhere on it, that is a reason to walk away rather than a bargain.
How is a toilet star rating calculated?
This is the part that surprises people. A toilet star rating is not based on the full flush volume alone. It is based on an assumed pattern of daily use, being four half flushes and one full flush per day. The average of that pattern is what gets rated.
Two consequences follow. First, the half flush volume carries most of the weight in the rating, because it happens four times as often. A suite with an efficient half flush can rate better than a suite with a marginally smaller full flush. Second, the rating only reflects real life if the half flush is actually used, which is worth mentioning to anyone in the household who presses the big button out of habit.
| Rating | What it broadly represents | Where you will see it |
| 3 star | The minimum water efficiency for toilets installed under state plumbing regulations. Typically a 6 litre full and 3 litre half flush. | Entry level suites and the current minimum for rental properties in New South Wales |
| 4 star | A meaningful step down in average water use from 3 star with no change in how the toilet is used. | The most common rating in current Australian bathroom ranges |
| 5 star and above | The most efficient suites available. Worth considering in water-restricted areas or where a certifier requires better than the minimum. | Premium and specified commercial work |
Older toilets are the real point of comparison. A single flush suite from before the scheme can use several times the water of a current dual flush suite over the same day, which is why replacing an old toilet is one of the more effective water saving changes available in a home.
What rating do you need? It depends on the job
New builds and full bathroom renovations
Where a toilet is being installed in new residential housing or as part of a renovation, state and territory plumbing regulations set a minimum water efficiency, and for toilets that minimum is at least three stars. Some jurisdictions set a higher bar than others, and areas under permanent water restrictions can require better again. Because the requirement is set at state and local level rather than nationally, confirm it for your address rather than assuming. Your plumber or building certifier will know, and it is a one minute question.
Replacing a single toilet in an existing bathroom
A like for like replacement is the simplest case, but the product still has to be a registered, labelled WELS product, and it still has to be WaterMark certified for a licensed plumber to install it. The bigger constraint on a straight swap is usually not the rating at all. It is the set-out, which is covered further down.
Rental properties in New South Wales
This is where the rules are most specific, and where landlords get caught out. From 23 March 2025, a landlord who wants to pass on water usage charges to a tenant must ensure the property has dual flush toilets with a minimum three star WELS rating. The same water efficiency requirements also cover shower heads, with a maximum flow rate of 9 litres per minute, and taps to internal kitchen sinks and bathroom hand basins, also with a maximum flow rate of 9 litres per minute. Taps for the bathtub, laundry sink, washing machine, dishwasher and outdoor taps are exempt from that flow rate requirement. There must also be no leaking taps or toilets at the start of the tenancy.
If the property does not meet those requirements, the landlord may not be able to pass on water usage charges. Water efficiency measures should be recorded on the condition report. If you are upgrading a rental bathroom, this is the section to send to the owner.
WELS and WaterMark are not the same thing
These two get confused constantly, and they do different jobs.
| WELS | WaterMark | |
| What it tells you | How much water the product uses, expressed as a star rating and a volume | That the product is certified as fit to be connected to a plumbing system |
| Set by | Water Efficiency Labelling and Standards Act 2005, administered by DCCEEW | Required under the National Construction Code, Volume Three |
| What it affects | Compliance with minimum water efficiency requirements, and your water bill | Whether a licensed plumber is permitted to install the product at all |
The practical point is that both apply to a toilet suite. Plumbing products listed on the WaterMark Schedule of Products must be WaterMark certified before a licensed plumber is permitted to install them. Regulated plumbing products also have to be WaterMark certified before they can be registered under WELS, which means a product properly listed in the WELS register has cleared both. A toilet with a great star rating and no WaterMark certification is not a toilet your plumber can legally install.
It is worth knowing this because uncertified plumbing products do appear for sale, particularly through overseas online sellers. Using them can also affect insurance cover if the product fails and causes damage.
How to check a toilet before you buy it
- Look for the water rating label on the product or the packaging, or the water efficiency details on the product page if you are buying online. Retailers are required to display them.
- Note the star rating and the WELS registration number.
- Check the registration in the WELS product register at waterrating.gov.au. It lists every registered product with its star rating and water consumption.
- Confirm the registration covers the pan and cistern combination you are actually buying, not a different pairing from the same range. Ask the supplier to confirm this in writing if you are buying components separately.
- Confirm WaterMark certification, which you can also check in the WaterMark product database.
- Give your plumber the model details before you order, so the set-out can be checked against your bathroom.
The thing that decides more toilet purchases than the star rating: set-out
You can choose the most efficient suite on the market and still find it will not connect to your bathroom. The waste connection is what determines that, and it comes in two broad arrangements.
- S-trap. The waste exits downwards through the floor. The critical dimension is the distance from the finished wall to the centre of the waste, and a toilet has to match the set-out that already exists or the set-out has to be altered.
- P-trap. The waste exits horizontally through the wall. The critical dimension here is the height of the outlet from the finished floor.
Because the measurement is taken from the finished wall and the finished floor, tiling changes it. If you are tiling the bathroom, the tile and adhesive thickness has to be accounted for when the set-out is checked, and this is a genuinely common cause of a suite not fitting after the tiling is done. Have your plumber confirm the set-out against your chosen suite before the tiling is set out, not after.
The related decision is the suite style. Close-coupled suites are the traditional arrangement with a visible cistern. Back-to-wall suites conceal the trap against the wall and are easier to clean around. Wall-hung suites use a concealed in-wall cistern and leave the floor clear beneath the pan, which needs a supporting frame built into the wall and has to be planned before the wall is lined and tiled. All three are available across a range of WELS ratings, so the style decision and the efficiency decision are separate.
Does a higher star rating mean a worse flush?
This was a fair concern about early water efficient toilets and it is much less of one now. Modern suites achieve efficiency through bowl geometry, the trapway design and the way water is delivered around the rim, rather than simply reducing the volume. A well designed four star suite is not asking you to flush twice.
Where the question does still have force is at the drainage end. In older homes with long or shallow-fall waste runs, reduced flush volumes can matter, and that is a question for your plumber about your particular drainage rather than a reason to choose a less efficient toilet. Rimless designs, which have become common, are worth a look for a different reason, which is that there is no concealed rim channel to clean.
Frequently asked questions
For toilets installed in new residential housing and renovations, state and territory plumbing regulations set a minimum water efficiency of at least three stars, which is typically a six litre full flush and three litre half flush dual flush suite. Some jurisdictions and areas under water restrictions require higher. Confirm the requirement for your address with your plumber or certifier, because it is set at state and local level rather than nationally.
For most households, yes. The step from three to four stars is the largest single reduction in average water use on the scale, and it changes nothing about how the toilet is used day to day. Over the life of the suite it is a meaningful saving on water bills, and in a household of four it adds up faster than in a single occupant home.
It is based on an assumed daily use pattern of four half flushes and one full flush. That average, rather than the full flush volume alone, determines the rating. It means the half flush volume carries most of the weight, and it also means the rating only reflects real household use if the half flush is actually used.
WELS tells you how much water a product uses and is administered under the Water Efficiency Labelling and Standards Act 2005. WaterMark certifies that a plumbing product is fit to be connected to a plumbing system and is required under the National Construction Code Volume Three. Products on the WaterMark Schedule of Products must be WaterMark certified before a licensed plumber is permitted to install them. A toilet needs both.
Yes. From 23 March 2025, a landlord wanting to pass on water usage charges to a tenant must ensure the property has dual flush toilets with a minimum three star WELS rating, shower heads with a maximum flow rate of 9 litres per minute, and taps to internal kitchen sinks and bathroom hand basins also at a maximum of 9 litres per minute. There must be no leaking taps or toilets at the start of the tenancy.
Only if it is WaterMark certified and WELS registered. Plumbing products on the WaterMark Schedule of Products must be certified before a licensed plumber may install them, and it is unlawful to supply a WELS-regulated product that is not registered and labelled. Uncertified products may also affect insurance cover if they fail and cause damage. Check both databases before buying.
Bring your set-out in and we will work through it
Toilets are the one bathware item where the measurement matters more than the design, and the fastest way through it is to bring the numbers with you. Our Smithfield showroom is open seven days, with toilet suites displayed alongside the basins, tapware and tiles that go with them.
Bring your existing set-out measurement or a photo of the current suite, and your plumber’s note on whether it can be altered, and we will show you what fits. Book an appointment for a design consultation, or send us the details and we will put a quote together for the bathware and the tiles at the same time.
