The change in water chemistry when you use an ion exchange water softener to create softened water is permanent and any effect will not wear off. This makes a water softener the perfect partner for any stored water system including a gravity fed system using a tank in the loft. To ensure the efficient operation of the water softener, it is advised that a delayed action ball valve is fitted to the tank. The water softener should be fitted to the mains water supply, with a minimum pressure of 1.7 bar.