Water softeners are used to help soften hard water and operate by removing the minerals (calcium and magnesium) that cause the hardness of the water, this is called ion-exchange. Salt softeners are the most convenient and can usually be installed under the kitchen sink, although a softener can occupy half a cupboard. There are pros and cons, so here are some pointers: The Water Softener needs to be topped up with salt every few months. London Plumbers only use qualified technicians. Water Authority Regulations insist that you fit a non-return valve between the water softener at the stopcock from the rising main. This prevents contamination of the drinking water supply. The Cold Water Tap on the kitchen sink is fed from the rising main at a point between the stopcock and the non-return valve, this means that drinking and cooking water remains untreated so you can still receive beneficial minerals. A Garden Tap should also be taken from the rising main between the stopcock and the non-return of otherwise youll be spraying expensive softened water on the garden. A Water Softener will need to be serviced, so it is a good idea to install valves for the system. These valves allow you to isolate the water softener and open the bypass valve which provides a supply of softened water whenever the softener is not used. You Will use less washing powder in your dishwasher and washing machine and your pipework will last longer. Your clothes and dishes could also be subject to less wear and tear. A Drain Cock should be fitted in the main water supply just above the non-return valve because the valve makes it impossible to drain water from any point above it. A Plumber is qualified to work on all domestic appliances. Finally, if your waste connection links directly with the trap under the sink you should fit both an anti-siphon valve and non-return valve to prevent dirty water returning back into the water softener.