Calcium is found abundantly in well water and is the primary source of hardness in water. In the human body, calcium contributes to bone mineral, helping to maintain hard and dense bone and tooth tissues, and aids in the function of enzymes. The amount of calcium in the water depends on the geographic location of the well, as well as the water treatment system if installed in the house.
Magnesium is another relatively abundant mineral in well water. It aids in muscle contraction, aids in heart and kidney function and contributes to enzyme activation. When magnesium ions, along with calcium ions, are present in the water system in very high concentration it can lead to the formation of deposits on appliances and fixtures, known as scale. This scale can block water pipes, decrease efficiency of water heaters and affect functioning of other water-using appliances.
Copper can also be found in well water in some regions. The source of the copper can be natural or due to the proximity of a copper mine or from copper piping in the water system. It is an essential trace mineral required by the body to promote energy production, in the production of pigment proteins and for efficient nervous system function. High levels of copper in well water may lead to pipe corrosion and copper contamination in the well, causing copper ions to leach into the water supply.
Water from some wells may also contain some harmful minerals, such as arsenic. Arsenic when consumed in even minute quantities over time can lead to poisoning, causing a range of symptoms such as diarrhea, nausea and numbness, as well as an increased risk of some cancers.
The composition of well water differs from region to region due to different geographical conditions. Well water thus can contain varying amounts of minerals at various places. Some other minerals also found in well water are iron, zinc, sodium, potassium, uranium, lead, chloride, fluoride, sulfates and nitrates. The sources of these minerals, too, can be natural, as well as artificial, like from manufacturing plants, gas stations and underground oil tanks. Minerals seeping from these units into the water table become part of the water.