Reverse osmosis technology is the most common method of producing usable low-mineral water from tap water. This technique is not used in the water circuit of the aquarium.
With the help of the tap water pressure (the use of a booster pump is also possible) and a special semipermeable membrane, the tap water is continuously divided into pure water and waste water. The pure water (permeate) contains very few salts, while the waste water (concentrate) contains all substances that are undesirable for aquaristics.