Microorganisms can be found in raw water from rivers, lakes and groundwater. While not all microorganisms are harmful to human health, there are some that may cause diseases in humans. These are called pathogens. Pathogens present in water can be transmitted through a drinking water distribution system, causing waterborne disease in those who consume it.
In order to combat waterborne diseases, different disinfection methods are used to inactivate pathogens. Along with other water treatment processes such as coagulation, sedimentation, and filtration, chlorination creates water that is safe for public consumption.
Chlorination is one of many methods that can be used to disinfect water. This method was first used over a century ago, and is still used today. It is a chemical disinfection method that uses various types of chlorine or chlorine-containing substances for the oxidation and disinfection of what will be the potable water source.
chlorine is a powerful disinfectant that kills most microorganisms, including bacteria, viruses and protozoa.
Pure chlorine is a gas and is extremely hazardous, however, stabilised chlorine products (liquids and solids) are safer, affordable and widely available. These products are commonly used for disinfecting drinking water in various humanitarian situations:
In a piped water distribution system.
Into water trucks.
Added to buckets / jerrycans of water collected from handpumps either manually by attendants or automatically by dispensers.
A key advantage of chlorination over other disinfection methods is that a residual may remain in the water, preventing recontamination. It is also relatively affordable, widely available, can be dosed without specialist equipment, and is easy to measure. However, it does need to be handled carefully, and the monitoring and dosing need to be carefully managed to ensure proper disinfection of the water.