In addition, many local health departments require well-water testing before a new well is put into service. However, no regulations govern water quality in private wells. There are no enforceable limits for particular contaminants and no requirements for tests to be made on any regular basis. Often, health agencies will make recommendations as to the suitability of well water based on standards established for public drinking water supplies. These, however, are only recommendations.
Many contaminants are natural.
Many are naturally occurring substances such as calcium, magnesium, silica and fluoride. More often they impact undesirable properties such as unpleasant taste, odor or hardness to the water. Some contaminants are living organisms, mainly soil bacteria. The ones which cause the most common odor, taste, smell and discoloration problems are the sulfur, iron and manganese bacteria. Occasionally, other types of bacteria, which indicate unsanitary conditions, are present.