Which water is the best for making coffee? But do you always get clear, pure water out of the tap? Sometimes when you turn the tap you might imagine you were in the public swimming pool: the smell of chlorine wafts towards you. It hardly needs saying that even if the pH value of the water is just right, chlorine will still completely denature your coffee. And if in addition you have copper pipes, or the hot water comes into contact with the occasional badly alloyed solder joint, this is extremely unhealthy. Drinking water is often obtained from the purification of surface water, and here nitrates, nitrites and heavy metals may be left in the water. Water filter systems can help rectify this. It is easy to find handy filter pots or systems in the shops, which can be mounted on your water supply. Water contains a whole range of 'invariable' constituents that also influence its taste. Even a small amount of these invariable substances are able to affect the difference between 'taste enhancing' and 'taste reducing'. - A certain amount of iron in the water is obvious to the taste. Too much iron in the water can even make the cream in your coffee turn green (but coffee-lovers know that cream is not necessary anyway). - Calcium makes water hard and hard water makes coffee bitter and neutralises its aroma. Tip for natural softening of water: Let the water boil for a while before using it to make your coffee. The calcium is deposited in the form of scale on the sides and bottom of the kettle, but this can be solved by using a descaler sold especially for this purpose. - Water also contains oxygen. Too much is bad for the taste of the coffee. When you take hot water from the tap, the bubbles of air often make it look white. This is a surfeit of oxygen. This white cloud usually soon disappears. The oxygen content can also be drastically reduced by letting it boil for a short while. But this should not be done too long, because the coffee aroma needs some oxygen to develop to the full. Other types of water - Most spring water contains a large amount of ¡¥invariable¡¦ constituents and often exceed the levels of taste one needs. If you prefer to use bottled mineral water to make your coffee, check its composition first: the mineral content should be as low as possible. You can usually judge simply by the taste (for example, compare the taste of Evian with that of Spa Reine). - Well-water and rainwater are usually too brackish: unsuitable acidity, chemicals from pollution, bacteriological infection, too many mineral salts and various impurities make it totally unsuitable for consumption.