Learn about tap water

01、The origin of tap water

The water supply of our city began in 1874, and the Longan Spring underground water supply facility was first built in Lushunkou, which has a history of 125 years。For a long time, tap water has never been doubted as drinking water for city residents, so is tap water safe？

02、China's tap water low standard qualified

In the early 1970s, the United States first found that water contains trihalomethane, and proved that the substance has a carcinogenic effect on the human body。With the aggravation of groundwater and surface water pollution in our country, the speed of the existing processing equipment and technology of waterworks is far less than the speed of pollution of source water, so people have raised various questions about the safety and health of tap water。

The combination of organic matter in water and chlorine disinfectants produces halogenated compounds, many of which have been identified as cancer precursors, the main ones being volatile trihalomethanes and non-volatile haloacetic acid, the latter of which is 50 to 100 times the risk of cancer。As a result, many countries have strict controls on the use of chlorine。At present, urban water treatment generally adopts conventional treatment technology, limited by its purification function, the removal effect of organic matter in water, especially for small molecular organic matter is relatively poor。

At present, most of China's water plants still stay in the process of flocculation-precipitation-filtration - chlorine disinfection。However, in recent years, the waterworks in Beijing, Shanghai, Guangzhou and other big cities in China have reformed the traditional processing technology of tap water, increased the pretreatment and in-depth treatment, making the water quality of the waterworks has been greatly improved, and most of the tap water has reached the national drinking water standard when it leaves the factory。However, due to the problem of secondary pollution of the transmission and distribution network, the water that comes out of each family faucet is finally polluted to varying degrees。According to statistics, 76% of the country's water plants supply terminal tap water some indicators have not reached the national standard。

03、The main way of secondary pollution of tap water

Pollution of water quality by transmission and distribution network。The water from the water plant, although after a variety of treatment, but there are still microorganisms reproduce, re-propagated microorganisms all year round in the distribution pipeline, forming a biofilm, membrane aging and falling off cause the odor and taste of water, chroma increase。In addition, these microorganisms gradually develop resistance to disinfectants and are not easy to be killed, which increases the number of microorganisms in terminal tap water。

The secondary pollution of the intermediate water tank is serious in the transmission and distribution network system。According to statistics, there are 70,000 intermediate water tanks in Shanghai and 1 intermediate water tank in Guangzhou.More than 10,000, and many more in other cities。As a result of prolonged exposure, poorly sealed and poorly managed, the growth of bacteria, viruses, protozoa and algae in these tanks contaminates the water quality。Every year, there are reports of red worms found in household tap water in Guangzhou, which is caused by the middle tank。In addition, rotting animal carcasses in individual intermediate tanks can increase the stench and sour smell of the water。