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When I was a child, my friends who grew up in the countryside have the impression that most of them will have a well, and they can't do without carrying water for cooking at home. However, it seems that there are no wells in the countryside now, and no one wants to drink the well water.
Chinese have drunk well water for thousands of years, why is it that no one is drinking it gradually?
Above-ground water is more susceptible to disease
The continent was one of the first countries in the world to notice groundwater and began to exploit it.
In the early days of human development, all the tribes in the world drank directly from the natural water on the ground, and these water sources were often taken directly from rivers and lakes, so people often got sick because of the sediment and bacteria contained in them.
It is understood that thousands of years ago, the ancestors of Indians began to use charcoal fire to boil and purify the water source taken from the river.
During the Ming Dynasty, the mainland began to add alum and other materials to precipitate the impurities in the natural water, and the reason why the mainland learned to purify the water source so late is also because we did not exploit the river water on the ground for a long time.
It turns out that there is such a well site in Yuyao, Zhejiang, and according to people's inference of its age, it may be 5,600 years ago that the mainland began to explore the water source underground.
At that time, in order to be able to dig a well to extract water, we usually made an opening in the spot with a radius of one meter, and then opened down to a depth of about 25 meters until we could extract water from the shallow underground.
Over time, we have gradually improved from the design of wooden wellheads to the design of stone wellheads, which greatly increased the service life of wellheads, and the way of collecting water has evolved from simple wooden barrels to pulley tools.
But how did our ancestors know that water would form underwater? It turns out that the earth's water sources have been going through a large cycle, and the surface water sources will be transpired due to high temperatures, and after the water vapor accumulates to a certain extent, it will form rainfall and return to the earth.
The reason why the well water is cleaner is that when it falls in the form of rainwater, it soon seeps into the surface through the rocks and sediment crevices, and it has already undergone initial filtration and precipitation compared to river water.
To put it simply, while our ancestors in other countries around the world were still getting sick from drinking river water, we have been clever enough to start using cleaner underground water sources.
The well water is no longer what it used to be
In fact, well water is also facing the dilemma of being less than the upper than the bottom, and the well water used to appear due to human needs, and now it is gradually retreating into the background because it cannot meet human needs.
As we all know, since the Ming and Qing dynasties, the total population of the mainland has ushered in a great increase. However, in a hundred years, the number of people on the mainland has increased from 100 million to 400 million, and the increase in population has not only increased the demand for food, but also the demand for water is also very urgent.
Normally, there are not too many wells in the village, but the number of people drinking water is increasing, which makes us start to think about whether we can get more water through other means.
Therefore, in modern times, the first water supply system in the mainland, "Longyin Spring", was born in 1888, and in modern times, we also use this as a base point to seek to lay tap water pipelines throughout the country.
During this period, the efficiency of pipe laying in mainland China was consistent with the speed of urbanization in various places, and at the same time, with the start of many factories and enterprises, the quality of aboveground water also increased from containing sediment, animal carcasses and germs to adding a chemical substance harmful to the human body.
Shallow groundwater is still unable to block the infiltration of these chemicals, so the quality of these water sources will gradually not meet people's demand for clean water.
In addition, echoing the water supply system, the mainland's propaganda on the safety and sanitation of food and water sources is increasing, and people also learned at this stage that the well water that people drank for thousands of years was not a perfect clean water resource.
As a result, most people, with the exception of a very small number of people, have begun to reject water extracted from drinking wells, and rivers as above-ground water are considered only suitable for use, not for drinking.
自来水杀出一条道
Tracing back to the source, in fact, the source of tap water is also groundwater and surface water, but the cleanliness of the same water source is very different.
According to statistics, in 2017, the length of tap water supply pipelines in the mainland has been as high as 790,000 kilometers, and the total water supply is 59.3 billion cubic meters.
So why does the mainland go out of its way to promote the use of tap water? It turns out that the relevant departments have already improved the water quality in places we can't see, and the water needs to go through at least six steps of purification from the outlet plant to the people's homes.
First of all, the mined water source will be injected with a certain amount of flocculant, which can allow small impurities and suspended solids in the water to accumulate and form large flocs. After a period of reaction, these impurities settle to the bottom of the tank in the next step of the reaction sedimentation tank.
After the initial purification, the water will be transported to the filter tank, and after precipitation again, it will be sent to the activated carbon adsorption tank through the pipeline, which can easily adsorb mercury, chromium and other chemicals in the water to further clean the water.
At this point, the quality of tap water is very different from that of well water, but even then, we need to do the last step, which is to put bleach powder to eliminate the chlorine in the water as much as possible.
According to the standard given by the World Health Organization, the standard of chlorine in tap water is 5mg/L, but the mainland can maintain the value at 1mg/L. It can be said that in order to allow people to drink clean water, the mainland began to lay out the layout in the fifties of the last century.
Now, all the efforts are beginning to show benefits, you know, people only after a simple boil to drink the well water, but the tap water is after the well water or river water, and then go through a six-step purification process to let the water into the households.
At this time, people have to boil and purify the tap water, so everyone must have an answer to whether we should drink tap water or well water.
Information sources:
Popular Science China 2022-08-10 Why does bottled water expire while well/tap water does not?
Popular Science Times 2024-03-22 Love water and save water Feel the wonderful world of water
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