Owners of private water supplies have no legal obligation to test their water. The only exception occurs in some states when a home is built or sold. For personal protection. These organisms do not cause disease but their presence indicates that disease organisms could be present. Because of the high probability of the presence of coliform organisms, a water test is highly recommended.
Corrosive water is the most common problem followed by bacterial contamination.
When a drinking water standard is set for radon this is likely to become a widespread problem.