A process and assembly subjects water to physical treatment to prevent the precipitation of solid substances in downstream water installations e.g. pipes. The assembly has a water treatment chamber (2) with an inlet (5) and an outlet (6). The novelty is that: (a) the treatment chamber (2) has an electrical heating element (3) which is linked to a regulator and control unit (7) and a temperature sensor (4); (b) the heating element phases are regulated to maintain the water temperature within a pre-determined maximum and minimum range; (c) the resulting calcium deposits remain in the chamber (2); and (d) water entering via the inlet (2) is directed by a tube (10) straight to the heating element (3).
