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Drinking Water

Testing for chlorine in drinking water

October 11, 2011
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Today, water is becoming even more of a precious commodity than ever before, which is why it is of the upmost importance that your customers drink the highest quality of water. Using chlorine is one way water treatment facilities keep water free of bacteria and harmful organisms, but too much chlorine in the water supply can also be hazardous if not reduced before coming out of your customers'' tap.

Know your residuals

Responsible water treatment dealers take several steps before treating water with significant chlorine. First, dealers should know about chlorine residuals. "There are different kinds of chlorine residual," says Ivars Jaunakais, who is an analytical chemist, speaker and educator as well as president of Industrial Test Systems. "You can have free chlorine and you can also have chloramines."

Free chlorine is the residual that consists of dissolved chlorine gas, hypochlorous acid and hypochlorite ions; chloramines are the combination of chlorine and ammonia.

"The different forms occur since many municipal treatment plants will chlorinate, but because of EPA regulations for trihalomethanes (THMs) they neutralize chlorine by adding ammonia to form the chloramines," explains Jaunakais.

Power of POU and testing

While chlorine and chloramines are great tools for disinfecting water, they need to be filtered out eventually and here lies an opportunity for the water treatment dealer. By being aware of the municipality''s use of chemicals, including chlorine, dealers can provide an effective solution and win the sale with community awareness.

"[Customers] need the chlorine because when the water is traveling from the plant to [their] homes, you want to make sure that water stays pristine," says Jaunakais. "That''s why POU is a wonderful device that cleans up the water to remove the chemicals added at the municipal treatment plant."

Moreover, there are two ways to test for chlorine: Test strips and test kits. Some tests will look for both free chlorine and total chlorine.

"If you want to know whether you have the chlorine or the chloramine compound, there are pretty simple tests to distinguish between one or the other and quantify how much free chlorine and chloramines you have in your water," says Jaunakais. "Typically, you can use the DPD system where the DPD instantly reacts with the free chlorine compounds to form the red color. Then, when you add potassium iodide to the DPD it will react with both chloramine and chlorine. The difference between the free chlorine reaction versus the total chlorine reaction gives you the chloramine reaction."

Breakpoint chlorination

Breakpoint chlorination is the process in which chlorine is added until all chlorine demand compounds are eliminated. What you have left is called free chlorine residual. Treatment plants have been using this process for years to eliminate chlorine demand compounds on a polishing and full scale basis.

During this process the water reacts with reducing compounds in the water that soak up the chlorine. Then, the chlorine reacts with the ammonia and the organic compounds found in untreated water. Next, the water reaches the breakpoint where the chlorine demand has been totally satisfied.

"After the breakpoint chlorination is determined, the treatment plant will then add chlorine to a big tank of water and dose it at a certain level in parts per million depending on what they''ve found," says Jaunakais. "Which will neutralize all the contaminants in the water."

Health effects from chlorine

According to Jaunakais, water treatment plants do a great job of making sure all American citizens have healthy, clean water, but there are three considerations in the water that your customers should be aware of: Fluoride, metals that corrode from plumbing and the added chlorine.

"Health wise, you don''t want to drink that stuff when it gets to your tap. You want to filter it out," says Jaunakais. "While chloramines are harmful, [they are] not so much when you drink them, but everyone needs to be aware of inhalation concerns. When you inhale chloramines, they pass through your lungs and readily elevate the chloramines in your bloodstream."

Chlorine is used as a disinfectant for drinking water and in swimming pools to help eliminate bacteria and odors. In water, the chlorine reacts to form hypochlorous acid and hypochlorites, and could potentially be harmful if consumed.

The main health effect that comes from drinking too much chlorinated water is bladder cancer.

"If you drink chlorinated water for 20 years or more it can increase your chances of having bladder cancer," explaines Jaunakais. "The possibility of bladder cancer for people who drink well water that has not been chlorinated versus city people who drink chlorinated water has been documented very carefully [over the years]. There are real, clear statistics that show chlorinated water increases the chances of bladder cancer."

Drinking chlorinated water over a long period of time may also cause a person to develop asthmatic conditions.

Trihalomethanes are one of the more dangerous byproducts of chlorine that have been proven to have a negative effect when coming into contact with humans. Inhaling THMs can affect the body''s central nervous system and cause abnormalities to the liver and kidneys.

It is vital for the protection of your customers that you make sure water is tested correctly and that there are no short- or long-term risks present in their water before suggesting treatment or pretreatment.

"Our society is preoccupied with living forever, and you don''t live forever if you consume toxic chemicals," says Jaunakais. "That''s what the POU [devices] and the whole water industry are based on … how to make our drinking water safer."

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