Water Dispensers
Reverse osmosis
Term from the vending glossary
Water filtration technique that, through pressurization (4–10 bar), removes nearly all dissolved salts, heavy metals and pathogens from tap water. Result: very pure, tasteless water (TDS <10 ppm). For POU sparkling water dispensers, frequently combined with a remineralization stage, because pure water tastes bland.
In reverse osmosis, a pump pressurizes water against a membrane that allows through only water molecules. Dissolved salts, limescale and most trace contaminants remain behind. The process delivers the most comprehensive water treatment available in vending machine design.
However, there are two costs to this approach. First, concentrate is produced and discharged — depending on the unit, a considerable fraction of feed water. Second, the result is so low in minerals that it must be re-hardened for coffee. Reverse osmosis therefore makes sense where tap water is very hard or heavily contaminated, not as a general improvement.