Chlorination is probably the most common method of treating microorganisms in water. This method is mainly used by water utility companies in order to kill microorganisms in water right from the water production site up to the consumers water tap.

Water treatment against microorganisms is very important especially when the water is supplied from lakes and rivers etc. Rivers and lakes may contain high levels of pathogens as a result from inadequately treated sewage discharges or non treated discharges. In some cases combined sewer systems may discharge untreated sewage during rain storms.

Chlorine is often used as a disinfectant in the form of a hypochlorite solution that is injected to the water system.


•         Effective against free bacteria floating in the water

•         Low life cycle cost



•        Smell and taste of the water is affected

•        Sensitive to pH-value of the water. At levels above 7,5 the disinfection effect is reduced 

•        Long term effect on bacteria is limited

•        Biofilm in hot water tank and pipes are medium affected