Then there was the reader with her borehole water supply. Although it's low in bacteria, it has levels of iron that are above the permitted standard. Is this dangerous, and, if so, what can she do? Well, one remedy is to become a blood donor as excess iron in the blood is a problem for men of all ages, and for postmenopausal women, and can cause heart attacks, says one reader. Another reader is less worried, and urges our reader to drink a glass of water from the borehole every day. It's a chalybeate spring, the type that many spas have been built around. Our reader isn't the only one to have a borehole water supply. Another reader had hers drilled in her back garden after it was found by a dowser. She has added a UV bio-filter as a precaution against contamination from animal slurry and crop sprays. She also has the water tested every year. One of her friends also had a borehole, which produced water that was reddish in colour from iron deposits, and so he had filters installed to purify it.