'I have a water softener so why do I need a water filter'? This may be useful if you were wondering... This is a not unreasonable question as both systems improve the quality of your mains water but in very different ways. A water softener alters the make up of the dissolved minerals in the water whereas a water filter actually removes them to produce pure water with no dissolved mineral content. The resin in a water softener exchanges calcium and magnesium minerals for sodium based minerals. The limescale that you see around the house is basically calcium carbonate and a water softener converts the dissolved calcium carbonate to dissolved sodium bicarbonate, which is much more soluble than its calcium equivalent and does not form limescale and therefore allows soaps to work better and stops scale build up on things like bath taps, showers and shower screens and any other water using device. A Race Glaze water filter uses a slightly different resin that doesn’t exchange anything, but simply absorbs all of the dissolved minerals in the water leaving nothing behind. For example, if you took an average 1 litre jar of hard water, the same volume of softened water and also filtered water, and then evaporated away the water and measured what was left, the hard water would typically have between 280 and 380 milligrams of minerals left behind (for a typical hard water area), the same for the softened water (only the minerals would be in a different form) while the filtered water would have less than 5 milligrams, probably closer to 1 milligram of dissolved minerals. It is these minerals that cause spotting on the car once washed and while the spots that occur with softened water are generally paler and not as noticeable as with hard water, they still occur. The filtered water with the close to zero mineral content will leave no spots however, as there is nothing left in the water to cause the spots. Race Glaze Refillable 0ppm Water Filters are available in 3 sizes at www.raceglaze.co.uk, from £99.00.