Skip to Content

Why use chlorine in water?

Using chlorine in water

The use of chlorine in water is very important because chlorine plays a role in eliminating pathogens and making water safe for use and consumption. The main reasons for using chlorine in water are as follows:


1. Disinfection

  • Chlorine can eliminate pathogens that cause diseases in water, such as
    • Bacteria: such as Escherichia coli (E. coli), Salmonella
    • Virus: such as Hepatitis A virus (HAV)
    • Protozoa: such as Giardia lamblia, Cryptosporidium
  • Chlorine disinfection helps reduce the risk of disease outbreaks, such as cholera and typhoid.

2. Prevention of contamination during water distribution

  • When chlorine is added to water, a residual substance known as free chlorine is formed, which helps prevent the water in the piping system from being contaminated with new pathogens during the distribution to users.

3. Removal of Organic Substances in Water

  • Chlorine helps to oxidize organic substances that may serve as food sources for microorganisms in water, such as leaf litter, chemicals in wastewater, or rainwater.
  • Reducing these organic substances helps to decrease the growth of pathogens in the water distribution system.

4. Reducing Unpleasant Odors and Tastes

  • Chlorine helps eliminate unpleasant odors and tastes in water, such as musty smells or the odor of organic substances caused by algae and microorganisms.

5. Control of Drinking Water and Utility Water Quality

  • In the water supply system, the use of chlorine is an important part of the process to make water clean and meet standards.
  • Chlorine is often used in conjunction with other processes, such as filtration and sedimentation, to produce water that is suitable for consumption.


Precautions Regarding the Use of Chlorine

  1. Appropriate amount:
    • Chlorine must be used in appropriate amounts according to standards, such as 0.2-0.5 milligrams per liter for drinking water.
    • Excessive amounts may cause a chlorine smell and taste in the water.
  2. Formation of Chemical Residues (Byproducts):
    • Chlorine may react with organic substances in water, resulting in byproducts such as trihalomethanes (THMs), which can be carcinogenic if present in high concentrations.
  3. Chlorine allergy symptoms:
    • Some people may have allergic reactions or irritation to chlorine, such as dry skin or stinging eyes.


Alternative options for disinfecting

Although chlorine is a popular method, there are other ways to disinfect water, such as:

  • Using UV Radiation: Utilizing ultraviolet radiation to kill germs without leaving any residue
  • Using ozone: Highly effective in killing germs, but more expensive than chlorine
  • Boiling Water: For Small Amounts of Water in the Household


Types of water storage tanks