Leaching refers to the process by which trace amounts of copper are picked up by the water flowing through the plumbing system. This can happen if the water is slightly corrosive, which is common in homes that get their water from a well. Small amounts of copper in the water are not harmful, and in fact copper is a micronutrient essential for all living things. Small amounts of copper are common in all water, but elevated amounts can cause health problems. The most obvious sign that your pipes may be leaching copper into your water is the presence of blue or green stains on your taps, showers, toilets, etc. At low levels of copper, water can cause staining and still be safe to drink. If your water tastes metallic or bitter, that is a sign that you may have higher levels of copper, and you should get your water tested.