Bacteria can be introduced in a well system in several ways. Some examples include: surface water leaking into the well from damaged or rusted well casing, damaged or incorrectly installed pitless adaptor, main well casing failure, and improper well service. The type of bacteria present will govern the treatment method. Examples of treatment would be; Chlorination of the Well, Pressure Chlorination of the Well, UV, Chlorine Injection, or Ultra-Filtration.