Chlorine standard for drinking water

Chlorine standard for drinking water

The chlorine standard for drinking water according to Standard Organization 1053 is 0.5 to 0.6 mg / l. Methods for disinfecting drinking water are always used, the most important being chlorination. Chlorination is done to improve the microbial health of water, control the growth of micro-organisms and prevent the re-growth of water organisms. Chlorine is a disinfectant. Disinfectants are substances that are added to water during the treatment process, especially for drinking purposes, to prevent the growth of germs in the water. Chlorination can be very hazardous to human health because of its toxicity, but since adding chlorine to water can be much more dangerous, the World Health Organization has stated that the consequences are far less than its benefits and better. It has to be done.

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Research has shown that the likelihood of cancer being caused by exposure to chlorinated water in pools is 25 per cent and in drinking water 6 per million.


for chlorination of water, they usually use hypochloroacid, which is obtained by using calcium hypochlorite salt. This salt in water converts to hypochlorite ion. During the chlorination process, the acidity of the water should be monitored, highly acidic PH causes corrosion of the material, and the advantage of alkaline PH is that the pool water prevents the conversion of ammonia to chlorine, which is detrimental to the health of the eye. Materials such as sodium bisulfate or sodium carbonate, etc. are used to adjust the pH of the water so that the equilibrium shifts to the production of hypochlorite acid which is more disinfecting.

One of the problems with the chlorination process is the production of organic chlorides, which are highly toxic and hazardous substances. For example, chlorides reacted with toxic phenolic compounds with a nasty odor. Another toxic and dangerous substance is chloroform, which is produced by the interaction of chlorine with hypochloroacid with water-soluble organic matter. Cloform in the water can cause anesthesia, respiratory paralysis and death. To avoid this danger, substances that do not produce chloroform are used, such as chlorine dioxide.


The different forms of chlorine used for chlorination of drinking water are:

  • Cl2 gas
  • Chloramine NH2 Cl and NHCl2
  • High Test Hypochlorite( H.T.H)
  • Clo2 Cl2 Dioxide

Chlorine is the first choice in many disinfectants because it is affordable and inexpensive and easy to use. Another compound that is added to water as disinfectants is chlorine ammonia, but its mechanism of action is slower than chlorine. Other chlorine compounds that are added to the water during the disinfection process include perchlorine or H.T.H or hypochlorite, which has a high percentage of chlorine and is used in drinking water for purification purposes. Perchlorine is sold as white powder by various factories producing laboratory materials. Other materials used in the chlorination process are sodium hypochlorite solution which can be used. Although there are many potential hazards to chlorination processes, chlorine is still used as a water disinfectant.

Chloride is stable in water because chloride ions usually do not undergo reactions such as oxidation-reduction, adsorption and bio-conversion. In the past, sodium chloride was used as a tracer because of the stability of the chlorides in the water, but nowadays it is used as dyes and radiators. The standard chloride ion concentration in uncontaminated freshwater is usually less than 10 mg / l. Increasing the concentration of chloride can be a sign of contamination and pathogenicity. As the high chloride content in water causes corrosion of metal structures and pipes and is harmful to many plant species, it is usually recommended that chloride concentrations in urban water be less than 250 mg / l, in less irrigated plants. Of 100 mg / l, and less than 50 mg / l in industrial applications.

Methods for determination of chloride concentration in drinking water can be described by argentometric titration, mercuric nitrate titration, potentiometer, self-free cyanide, flow analysis and capillary ionic electrophoresis. The sum of hypochlorous acid (HOCl) and hypochlorite ion (OCl-) in drinking water is said to be the amount of free chlorine remaining, with the virtual values ​​given in the following tables.

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