Waterless Urinals
A waterless urinal is a urinal that uses no flush water. Urine drains by gravity through an odour seal in the outlet, and that seal stops sewer gas coming back into the room. The seal is either a layer of barrier oil that floats on top of the urine in the trap, or a mechanical one-way valve that opens under flow and closes behind it.
Last updated October 2026. The Urinal Shop has supplied, serviced and troubleshot urinals from every major waterless brand in Australia since 2010.
How a waterless urinal works
A waterless urinal looks like a standard urinal. The difference is in the outlet. Instead of a water-filled trap that has to be flushed, it has an odour seal, either a replaceable cartridge or a trap insert, sitting below the grate.
- Urine runs down the bowl into the outlet.
- It passes through the odour seal: down through the oil layer, or through a valve that opens under its weight.
- Gravity carries it into the sewer, exactly as it would from a flushing urinal.
- The seal closes behind it, blocking sewer gas.
There is no water supply, no cistern and no flush valve to install. Like every plumbing fixture sold in Australia, a waterless urinal must be WaterMark certified, and the certification covers the urinal together with its odour seal. That is why replacement cartridges and inserts should be genuine.
The two types of odour seal
1. Barrier oil seal
A barrier oil seal is a trap filled with urine and topped with a layer of oil. The oil is lighter than urine, so it floats on top and forms an airtight cap. Urine passes down through the oil, displaces the liquid below, and drains away. The oil stays on top. ZeroFlush’s barrier oil, for example, is a refined plant oil with a specific gravity of 0.87.
Oil systems have no moving parts and are cheap to run. The weak point is the oil itself: water poured into the urinal or a high-pressure clean can wash it out, and once it is gone the urinal smells. After every service the trap needs the correct volume refilled. Our guide to waterless urinal oil explains how barrier oil works and how to top it up.
2. Mechanical one-way seal
A mechanical seal is a valve or membrane in the outlet that is closed at rest. The flow of urine opens it, and it closes again once flow stops. There is no oil to top up or wash out. The cartridge or valve wears and has to be replaced on schedule.
The Caroma H2Zero is an example: its cartridge carries a Bio Seal that opens during use and self-seals immediately afterwards, plus a replaceable Bio Fresh deodorising block. Britex uses a mechanical valve, Urimat has its D-Valve, and Falcon has the HPKV.
The market is moving to mechanical
Barrier oil was the original waterless technology, and several major brands started there. ZeroFlush, Urimat and Falcon all began with oil, and all three now offer a mechanical seal: ZeroFlush’s EnviroSeal, Urimat’s D-Valve and Falcon’s HPKV. Mechanical seals remove the most common cause of waterless failure, which is barrier oil that has been washed out or not refilled. If you are replacing an older oil-based urinal, it is worth asking whether a mechanical seal fits your existing model.
Which brands use which seal
| Brand | Seal type | What gets replaced or topped up |
|---|---|---|
| Caroma H2Zero Cube | Mechanical (Bio Seal cartridge) | Cartridge and Bio Fresh block (H2Zero service kit) |
| ZeroFlush (ZF-101, ZF-201, ZF-501) | Sold in two versions: barrier oil insert, or EnviroSeal mechanical seal | Oil version: barrier oil top-up. EnviroSeal version: seal and BioPur tab |
| Uridan | Barrier oil (uriLOCK) | uriLOCK barrier oil top-up |
| Enware IFO Cero | Barrier oil | Barrier oil top-up |
| Falcon | Barrier oil (Velocity cartridge), now moving to mechanical (HPKV valve) | Velocity: barrier oil and cartridge replacement. HPKV: valve insert |
| Urimat | Barrier oil originally, now moving to mechanical (D-Valve) | D-Valve replacement |
| Britex Barren | Mechanical valve | Valve (Britex waterless outlet assembly) |
| Waterless Co (Sonora, Baja, ANZA) | Barrier oil (EcoTrap insert) | Barrier oil; EcoTrap insert |
Cartridges, inserts and oils for all of these are in our waterless urinal cartridges range. If you are not sure which system you have, send us a photo of the outlet with the grate removed and we will identify it.
When a waterless urinal is the wrong choice
Waterless suits most commercial washrooms, but not all of them. We will tell you not to go waterless if any of these apply:
- Copper waste pipe. Undiluted urine attacks copper. ZeroFlush’s installation instructions, for example, specify no copper drainage immediately downstream of the urinal. Replace the copper with PVC first.
- Long drainage runs with poor fall. With no flush water behind it, urine relies entirely on gradient. Long, flat runs let it sit, and scale builds up until the pipe blocks.
- No one to maintain it. A waterless urinal that misses its servicing will smell within weeks. A flushing urinal tolerates neglect far better.
If any of those describe your site, a low-flush urinal is usually the better answer.
Maintenance: what you are signing up for
- Clean daily if the urinal is used by more than 10 people a day, with a urinal-safe cleaner sprayed and wiped. Don’t use a bucket of water or a hose.
- Never pour water or mop water into it. On oil systems, it flushes the barrier oil into the sewer.
- Service the seal on schedule: top up the oil, or replace the cartridge or valve, at the interval the manufacturer sets for your traffic. Don’t wait for the smell.
- Watch the waste pipe. Concentrated urine leaves scale in the pipe over time. A urinal-specific descaler keeps it clear.
- Use genuine parts. The WaterMark certification covers the urinal with its own odour seal.
Our troubleshooting videos show cartridge and trap servicing step by step. If you would rather not do it yourself, we offer urinal servicing.
Do waterless urinals smell?
Not when they are looked after. When someone tells us a waterless urinal smells, the cause is almost always the seal: oil that has run low or been washed out, or a cartridge well past its replacement date. Fix the seal and the smell goes. A well-maintained waterless urinal is often less smelly than a flushing one, because there is no standing water in the bowl for bacteria to grow in.
How much water does a waterless urinal save?
All of the water the urinal would otherwise flush. As an illustration, a flushing urinal using 2 litres per flush, flushing 5 times an hour for 10 hours a day, 6 days a week, uses about 31,000 litres a year. A busy pub or stadium urinal uses several times that. Your actual saving depends on your existing flush volume and how often it flushes, so check the figures for your current fixture.
Frequently asked questions
How does a waterless urinal work?
A waterless urinal uses no flush water. Urine drains by gravity through an odour seal in the outlet, and the seal stops sewer gas coming back into the room. The seal is either a layer of barrier oil that is lighter than urine and floats on top of the trap, or a mechanical one-way valve that opens under flow and closes behind it.
Do waterless urinals smell?
Not when they are maintained. Smell from a waterless urinal almost always means the odour seal has been neglected: the barrier oil has run low or been washed out, or a cartridge or valve is overdue for replacement. A urinal used by more than 10 people a day should be cleaned daily, and water or mop water should never be poured into it.
Can waterless urinals be connected to copper pipe?
No. Undiluted urine attacks copper, and manufacturers such as ZeroFlush specify no copper drainage immediately downstream of the urinal. Copper waste pipework should be replaced with PVC before converting to waterless.
What maintenance does a waterless urinal need?
Daily cleaning with a urinal-safe cleaner, no water poured into the bowl, and topping up or replacing the odour seal on the manufacturer’s schedule. Oil-barrier traps need the correct volume of oil refilled after every service. Mechanical systems such as the Caroma H2Zero need their cartridge replaced.
When is a waterless urinal the wrong choice?
When the waste pipe is copper, when the drainage has long runs with poor fall, or when nobody will maintain the urinal on schedule. In those cases a low-flush urinal is usually the better option.
Not sure which waterless urinal suits your site?
We stock waterless urinals from multiple brands, so we recommend what fits the site rather than a single product. Call 1800 874 625 for advice on choosing, converting or troubleshooting a waterless urinal.