Cation exchange typically uses sodium or potassium chloride, and can also treat for some forms of lead and radium. It is also commonly used to soften water. Disinfection Technologies Disinfection technologies kill or screen-out biological contaminants present in a water supply. Chlorination, microfiltration, ozone, and ultraviolet light are the four major technologies used to disinfect water. Chlorine can effectively treat biological pathogens like coliform bacteria and legionella , though it is ineffective against hard-shelled cysts like those produced by Cryptosporidium .
Chlorination also treats for organically-related taste, color, and odor problems.
Chlorine is typically fed directly into a well, or into a retention tank where concentration and contact time can be controlled. Chlorination is effective for treating pathogens like coliform bacteria and legionella , though it is ineffective against hard-shelled cysts like Cryptosoridium and Giardia lamblia . Other chemicals like bromine and iodine can also be used to disinfect water through much the same process as chlorination, though they are not as frequently used. Microfiltration Microfiltration uses a filter media with a pore size smaller than 0.2 microns to physically prevent biological contamination from passing through. Ceramic and solid block carbon are commonly used to provide microfiltration.