Tap water contains heavy metals, long-term drinking will cause cancer? Is the yellow water still drinkable? tell you the answer
In the US city of Flint, 8,000 children were exposed to lead poisoning due to tap water problems, and 77 million people were affected by drinking water.
The reason is that because of financial difficulties, in order to save money, the government changed the Lake Huron water previously purchased from Detroit to the nearby Flint River, and the pipeline connected to the water source was found to contain a lot of lead .
In China, most families drink boiled boiled water for a long time, and there have been exposures about the quality of tap water in some areas, and even there has been a saying that " drinking tap water for a long time will lead to the accumulation of heavy metals, which is detrimental to health ".
So, is drinking boiled boiled water for a long time really harmful to the body?
1. Tap water contains chlorine. Long-term drinking will cause cancer?
The first thing to be sure is that tap water does contain chlorine. Is this substance safe?
The water source of tap water generally comes from rivers, lakes, reservoirs, etc., and then to the waterworks, and then to the homes of residents. In this process, the processing technology of the water plant, the water supply pipeline and the roof water supply tank may all have an impact on the water quality .
Sun Ting, a water quality inspector of Jinan Water Group, said that since the water quality is easily polluted, in order to ensure the safety of tap water, chlorine is indeed added. This chlorine (liquid chlorine or chlorine dioxide) is the last disinfection process in the water factory. The chlorine content It must be >0.3mg/L and <4mg/L to meet safety standards .
The tap water that can flow out of the faucet must meet the national "Drinking Water Sanitation Standard" (GB5749-2006), which stipulates 106 water quality indicators , which can be said to cover various factors in drinking water that may affect health.
Therefore, in theory, the tap water flowing from the faucet is safe .
Is chlorine in tap water harmful to humans?
Generally speaking, the free residual chlorine content in peripheral water is basically around 0.mg. Assuming that an adult drinks 2L a day, it will be less than 2mg at most, which is far lower than the NOAEL of free residual chlorine in water given by WHO. Visible toxic levels) safe intake: 15mg/kg per day.
That is to say, it is safe for a person to drink dozens of liters of tap water a day .
In short, tap water in daily life is safe to drink, but due to aging pipes and other reasons, there may be secondary pollution , so it is best to boil it before drinking it, and it is not recommended to drink it directly.
2. The tap water has turned yellow, can I still drink it?
Sometimes when we turn on the faucet after the water is turned off, we will find that the water that comes out is yellow. Is this water still drinkable? Generally speaking, the color of tap water turns yellow is mostly caused by two reasons.
First, the water pipes are aging. In some old communities, the water supply pipes are already rusted. When the water is turned on, the flow rate of the tap water suddenly increases, which will bring the rust and microorganisms on the wall of the aging water pipes into the water , making the water turbid.
The second is the secondary water supply pollution in the community . Some households have relatively high floors, and the municipal water supply cannot reach it (generally, it can only be supplied to the 6th floor or below.
At this time, only secondary pressurized water supply can be installed (mainly with or without negative pressure water supply equipment and water supply from reservoirs). If water from reservoirs is used, if it is not cleaned in time, poor water quality and yellowing may occur .
Is this yellowish water harmful to human health? It's not necessarily harmful, but one thing is certain, that is, the water that turns yellow must be of average quality .
So in this case, you can turn on the faucet first and let some water in, if the water becomes clear after a few minutes, it will be fine. If the water is still yellow or there is always such a situation, it is best to contact the community property and other units to check the water supply pipe network.
3. Tap water, mineral water, purified water, which one is better?
There are actually many types of water. In addition to tap water, there are also mineral water, pure water... It is also very common. Which water is the best?
1. Tap water
The tap water contains beneficial minerals, and the tap water that has passed the quality inspection can be safely drunk after being boiled. However, there are secondary pollution risks such as aging of the pipeline network, which should be avoided.
2. Mineral water
This kind of water contains a small amount of minerals such as calcium, magnesium, phosphorus, etc., but this is not the main channel for our mineral supplementation . Only 1% is absorbed from water every day , and the rest basically comes from food. It's enough for daily hydration.
3. Purified water
Generally speaking, the quality inspection standard of pure water is higher than that of tap water, so it can be drunk directly, but it basically does not contain trace elements, which is harmless and useless .
In short, daily hydration, no matter what kind of water is available.
And many people think that after the boiled water is boiled, scale will appear, which may be harmful to the human body. Is this true? Not really. The scale that appears is actually calcium and magnesium ions in the water that are heated to form calcium bicarbonate , which is harmless to the human body.
On the contrary, drinking some filtered water/artificial water regularly may have potential impact on human health. Because when the scale is filtered, it also loses the way to obtain minerals from drinking water , and minerals have a certain protective effect on human cardiovascular health.
So what is the healthiest way to drink water?
1. The amount should be sufficient
It is necessary to ensure sufficient water intake for one day. According to the recommendation of the Dietary Guidelines for Chinese Residents (2016 Edition), adult men should consume more than 1700ml per day, and women should consume more than 1500ml , and they should drink water actively. Don’t wait until you are thirsty to drink water .
2. The temperature is suitable
Secondly, pay attention to the temperature of the water. Often drinking water above 65°C may cause cancer, so be careful to avoid it. The water temperature is around 18-45°C.
3. Boiled water is the healthiest
It is also important not to completely replace boiled water with pure water or beverages , because some of the nutrients in boiled water are not found in pure water, and beverages contain a lot of sugar. Regular intake may lead to obesity, which is not good for health.
Summary: Generally speaking, tap water that has passed the quality inspection will not cause problems such as "cancer" and "poisoning" that everyone is worried about. It can be drunk with peace of mind. Don't panic! Drinking enough water every day is very important for health, so everyone must drink enough.
References:
[1] "Does Tap Water Contain Chlorine? 》.Xiamen Disease Control.2019-12-27
[2] "Why does the tap water turn yellow, is it harmful to the body? 》. Healthy drinking water. 2019-06-27
[3] "Tap water, mineral water, purified water, mountain spring water... Which water is better to drink? The answer was unexpected! 》.CCTV Life Circle.2021-03-25
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