Why is chlorine used for the treatment of drinking water even though the gas is very toxic?

The Benefits of Chlorine

Potent GermicideChlorine disinfectants can reduce the level of many disease-causing microorganisms in drinking water to almost immeasurable levels.

Taste and Odor Control Chlorine disinfectants reduce many disagreeable tastes and odors. Chlorine oxidizes many naturally occurring substances such as foul-smelling algae secretions, sulfides and odors from decaying vegetation.

Biological Growth Control Chlorine disinfectants eliminate slime bacteria, molds and algae that commonly grow in water supply reservoirs, on the walls of water mains and in storage tanks.

Chemical Control Chlorine disinfectants destroy hydrogen sulfide (which has a rotten egg odor) and remove ammonia and other nitrogenous compounds that have unpleasant tastes and hinder disinfection. They also help to remove iron and manganese from raw water.

Water chlorination

is the process of adding chlorine (Cl2) or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc

 

 

Chlorine

Chlorine is one of the most versatile chemicals used in water and wastewater treatment.

This powerful oxidizing agent is used for

• Disinfection control of microorganisms
• removal of ammonia
• control of taste and odor
• color reduction
• destruction of organic matter
• hydrogen sulfide oxidation
• iron and manganese oxidation

 

 

 

 

 

Always when looking at the properties of chemicals and chemical compounds consider the concentration aspect!.

Chlorine gas released in high concentrations into the atmosphere (green cloud is around ppm) is as you say toxic

If metered in sparingly into water, will form Hypochlorus Acid which will over period of minutes degrade pathogens present in water, making it fit for human consumption. The residual level of chlorine in water if dosed properly will have no impact on humans at all, and by providing ongoing disinfection capacity is a benefit to humans. 

Microorganisms ( Bacteria ) can be found in raw water from rivers, lakes and groundwater So (Chloraination ) dosing chlorine and must be concentration less than 0.5 ppm to disnefetant 

the major reason to use Chlorine gas as disinfectant for water and wastewater treatment due to residual chlorine which makes purification for pipelines and reaches to the consumer tab

Chlorine gas is used in pre-treatment of water and is removed using GAC filters.Because it is not only toxic to human but also corrodes RO membranes.

In drinking water, chlorine is nil.

This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.

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.

i think its the matter of concentration of chlorine gas in the atmospher and the differance in characteristics of chlorine in compounded condition or being a ion.

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

Because chlorine in liquid feature dissolved in water and then it will sanitize the water and we can remove it from water, but gas it affects on our respiratory system and can cause death