Water quality safety has always been the topic of our concern, of which tap water is the lack of our side. So why is there so much chlorine in tap water? Where did it come from? Is there any harm to the human body? This chapter water quality online monitoring manufacturers to understand together with you about the residual chlorine in tap water related knowledge points.

Where Does the Residual Chlorine in Tap Water Come From?

In order to ensure the safety of the water quality, the waterworks will add chlorine disinfectant before the water is discharged, and there will be a surplus after that. In addition, the waterworks should not only ensure that there is a certain amount of residual chlorine in the water, but also ensure that the water reaches the end of the pipe network that is exposed to the user. Its purpose is, of course, to eliminate microorganisms (algae, pathogens, etc.) in tap water and in the tap water network.

So is More Chlorine in the Water Better?

As I have learned above, tap water must contain residual chlorine, and the worse your water quality, the higher the residual chlorine will be. It is to keep the number of microorganisms in the water below the standard! That is to say, in areas with serious water pollution, in order to inhibit the reproduction of the remaining bacteria in the water and maintain continuous bactericidal ability, the usual practice is to add chlorine. Is the more total chlorine in the water the better?

We know that the residual chlorine forms in water include free residual chlorine and combined chlorine. Free residual chlorine includes chlorine, hypochlorous acid, and hypochlorite ions. The combined chlorines include monochloramine, dichloramine and trichloramine.

In fact, China’s “drinking water sanitation standard GB5749-2006” for disinfectant indicators are also required, if chlorine gas or free chlorine preparations for disinfection, then the factory water allowance should not be less than 0.3mg/L, not more than 4mg/L, while the pipe network end allowance is not less than 0.05mg/L; If the use of chloramine disinfection, then the total chlorine in the factory water should not be less than 0.5mg/L, not more than 3mg/L, while the pipe network end allowance is not less than 0.05mg/L. So the amount of chlorine in water is regulated, not the more the better.

It is easy to add chlorine, but the control of the amount of chlorine added is the control of the total residual chlorine, which is a problem that the relevant departments must pay attention to. If the control is not good, the user drinks the tap water with a very heavy smell of bleach powder for a long time may be harmful to the human body. There are also many bad by-products when chlorine reacts with organic acids, which can lead to death. Although these dangers are generally found after instrument detection, can not be seen by the naked eye, but does not mean that it does not exist.

For example: “Researchers at a Wisconsin hospital in the United States found that:

Free residual chlorine in tap water and its derivatives “trichloromethane, carbon tetrachloride and other carcinogenic and mutagenic substances”, in addition to drinking GTRERTYfrom the mouth into the human body, there are a large part of people in the face, hand washing, mouth wash, from the skin, pores, hair into the human body.

According to reports, more than 80% of the residual chlorine and its toxic and harmful substances in water enter the human body from the skin.

Therefore, the residual chlorine in the water, impurities, pipes, water tanks and other water pollution has seriously affected human health.”

Therefore, although the residual chlorine can effectively sterilize the tap water, if the control is not in place, the excess will be harmful!

What Affects the By-products Produced by Chlorine Disinfection?

In fact, there are many factors affecting the disinfection by-products in drinking water, mainly including the following aspects:

1.Types and concentrations of pollutants in water. General surface water is seriously polluted with many kinds of pollutants, and the types and concentrations of by-products generated by chlorine oxidation are much higher than those of deep groundwater with light pollution.

2.The ph value of water, water temperature and bromine ions in water can affect the generation of disinfection by-products to varying degrees. The increase of the content of these three will increase the probability of trihalomethane formation in water.

3.The amount of chlorine injection can affect both the concentration level of disinfection byproducts and the distribution of their types. In addition, disinfection procedures, chlorine contact time, residual chlorine, season and metal ions all affect the production of disinfection byproducts.

Speaking of which, it is important to monitor the total residual chlorine before the water is discharged from the waterworks! How should we know if the total residual chlorine in the water exceeds the standard? The RCl900 total residual chlorine online analyzer produced by Hangzhou Modi is a fully automatic online instrument controlled by an embedded system. After the water sample and anti-interference agent are automatically injected into the reactor, the characteristic color developing agent is automatically added for color developing reaction, and the absorbance of the reactant is measured. The online analyzer can directly measure the total residual chlorine content in water through the absorbance value.