These processes have existed for more than 30 years but have never been really convincing in the domestic field. Most of the reasons are due to the kind of pipelines there are, to the properties of certain waters but mostly, to the speed of the water flow inside the installations. Concerning this last point, the speed of 2m/s is most commonly recommended. It is the same as 3 or 4 taps opened at the same time. A very rare situation within a household. This explains why these systems have never been so much developed on the consumer market. The ATEX’s (Technical Experimental Certification) that are delivered concerning theses processes by the CSTB, are never awarded to domestic systems because the speed of 2m/s is always included in the technical specifications during try-outs. They are therefore non included in this comparative, as they are not efficient.