A waterless urinal in a busy building saves between 80,000 and 160,000 litres of water a year. The arithmetic is simple and anyone can check it. What gets mentioned less often is that losing the flush also means losing the only thing that was diluting the urine, so maintenance stops being cleaning and becomes managing the chemistry in the drain.
Where the saving comes from
A conventional urinal uses 1.5 to 3 litres per flush, depending on the age of the installation. Older models with timer-controlled automatic flushing run even when nobody has been in the room — at night, at weekends, on public holidays.
At 150 uses a day and 2 litres per flush, a single urinal gets through around 110,000 litres a year. In a building with ten urinals that is more than a million litres.
What changes without water
Flushing was not only there to carry waste away. It diluted the urine and brought the concentration of uric acid in the outlet throat down. Without it the urine stays concentrated, the pH rises sooner, and struvite and calcium phosphate precipitate out considerably faster than in a urinal that is flushed.
A waterless urinal maintained as though it were a conventional one will block faster than a conventional one. That is a common reason why buildings go back to their old urinals after a year.
How it should be maintained
- A neutral cleaner and water. Never acid — over time it damages the glaze and accelerates scaling. Never chlorine — it kills the cultures that break uric acid down.
- A bio-enzymatic tablet in the throat. Here it is not a precaution but a necessity. With no dilution by water, breaking uric acid down is the only thing standing between you and scale.
- Regular cartridge changes if the model uses a liquid barrier. A spent cartridge lets gases through.
- An occasional flush with water — a few litres through the throat once a month carries away whatever has built up anyway.
| Conventional | Waterless | |
|---|---|---|
| Water use per year | 80,000 – 160,000 L | 0 L |
| Rate of scale build-up | Moderate | Considerably faster |
| Consumables | Bio-enzymatic tablet only | Cartridge and bio-enzymatic tablet |
| Sensitivity to the wrong product | Medium | High |
| Bio-enzymatic prevention | Recommended | Essential |
Where it makes sense, and where it does not
It makes sense in buildings with heavy, steady traffic: stadiums, railway and bus stations, large office complexes, factories, universities. There the water saving is substantial and maintenance is organised and regular in any case.
It does not make sense in buildings with low or irregular traffic, or where cleaning is done by an outside contractor with no specific brief. The water saving does not cover the risk of a blockage, and in practice the change in the maintenance regime never actually happens.
In those cases a conventional urinal with a bio-enzymatic tablet in the throat delivers most of the benefit — no odour, no scale — with a maintenance routine the staff are already used to.