As well as possible organic contaminants like the bacteria campylobacter, some campaigners say tap water is treated with too many chemicals. Aluminium and chlorine are added at treatment plants and are often not filtered out before they reach our homes. Copper traces in tap water may increase the risk of Alzheimer's disease, according to US studies. Added to these chemicals, limescale also stops water being PH-neutral, as it should be.

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