1. Why is chlorine chemical added to domestic water?

Waterborne diseases used to kill thousands of U.S. residents each year. After first being used in Jersey City, New Jersey in 1908, chlorination of drinking water spread rapidly throughout the United States and virtually eliminated waterborne diseases such as cholera and typhoid fever. Since then, chlorinated drinking water has played a major role in increasing Americans’ life expectancy by 50% in the 20th century. The US Centers for Disease Control and Prevention calls the process of chlorination. Chlorine in water is “one of the most important public health advances in American history”.

Chlorine kills disease-causing germs and makes the water safe to drink.

Besides killing dangerous germs like bacteria, viruses, and parasites, chlorine helps reduce unpleasant odors in water. Chlorine also helps remove slime bacteria, mold, and algae that commonly grow in water supply reservoirs, on the walls of water pipes, and in storage tanks. In fact, the US Environmental Protection Agency requires treated tap water to contain detectable levels of chlorine to help protect against germs reaching consumers’ faucets.

2. How is chlorine added to water?
A water treatment plant operator can disinfect drinking water using chlorine gas, liquid sodium hypochlorite (bleach) or dry calcium hypochlorite. Each of these sanitizers unleashes the power of chlorine chemistry to kill disease-causing germs in the water.

Chlorine has helped provide safe drinking water in the United States for over 100 years.

3. Do you know how long the US has used chlorinated drinking water?
Beginning on September 26, 1908, Jersey City, New Jersey became the first city in the United States to provide regular chlorinated municipal drinking water. Over the next decade, more than a thousand US cities adopted chlorination, which greatly reduced infectious disease.

How popular is chlorine to disinfect water?
Chlorine is by far the most commonly used drinking water disinfectant in all regions of the world. Today, about 98% of U.S. water treatment systems use some type of chlorination process to help provide safe drinking water. The US Environmental Protection Agency requires treated tap water to contain detectable levels of chlorine to protect against germs as it flows from the treatment plant to the consumer’s faucet.

And Vietnam is no exception, the use of chlorine chemicals to treat water becomes more popular because:

• • Easily remove odors and harmful substances in water
  • Highly effective sterilization against a wide range of bacteria
  • Disinfection with chlorine if the right dose and method will not cause harm to health
  • Chlorine is a cheap and easy to find chemical. Therefore, disinfecting water with chlorine is quite economical but highly effective

In addition to economic reasons – high sterilization efficiency. When chlorination of water saves a certain amount of chlorine concentration, it plays a role in preventing reinfection of treated water during transportation or storage of water.