Why can't tap water be drunk directly?
Due to insufficient attention to the management of urban water supply, so far, our tap water is sti
Why can't tap water be drunk directly?
Due to insufficient attention to the management of urban water supply, so far, our tap water is still not directly drinkable for the following reasons:
1. Eutrophicated water has high hardness.
▲ Source: d.ifengimg.com
The number of algae and microorganisms in water has increased, and the eutrophication of surface water in China has reached 70%. Carbonate rock is the main stratum in Beijing, which determines the high nitrate content in groundwater in Beijing.
According to the research of British National Institute, hard water will not directly harm health, but it will destroy or reduce the nutritional value of cooked food.
But hard water should be avoided for babies. This is because the milk powder itself contains nutrients such as protein and minerals, and the baby's internal organs are not fully developed. Excessive intake of mineral ingredients may cause indigestion and cause a burden on the baby's body, so soft water with low mineral content is more suitable for making milk powder.
▲ Risk map of arsenic pollution in China.
Source: Swiss Federal Institute of Water Science and Technology.
2. The drinking water standard lags behind
There are three internationally authoritative and representative drinking water quality standards in the world, namely, the World Health Organization's drinking water quality guidelines, the EU's drinking water quality directives and the US Environmental Protection Agency's national drinking water quality standards. China's current standards are lower than the World Health Organization's drinking water quality guidelines.
▲ Source: www.pinlue.com
3. Water pollution caused by the intermediate water tank of the transmission and distribution pipeline
Copper pipes or stainless steel pipes must be used to ensure that the secondary pollution of tap water after leaving the factory is within the range of direct drinking.
At present, tap water that has been deeply treated (generally activated carbon ozone) in China can be directly drunk after leaving the factory. However, the tap water pipes in China are generally old cement pipes and galvanized pipes, and the pipe walls are easy to corrode and pollute, thus increasing the dissolution of lead, so tap water cannot be directly drunk.
The high-rise water tank may not be taken care of by a special person, which is easy to breed bacteria and viruses, and there are more and more sediments in the water tank, and the water quality is even more worrying.
This is one of the reasons why many families don't consider high floors.
▲ ? Source: Network
Boiling can only destroy microorganisms in water. If there are nitrate and lead in the water, boiling water will increase the concentration of nitrate and lead, which is harmful and useless.
As for those of us who pay more attention to health, more and more families begin to buy water purifiers and drink pure water.
How to choose a water purifier?
▲ Source: Taobao
I searched for a water purifier in Taobao, and the first entry that appeared was "household water purifier". The top home pages are Haier, AO Smith, Xiaomi, Qinyuan and Angel. However, the advertisements of each brand are dazzling. As a water purifier, Xiaobai doesn't know how to choose.
So ... how to choose?
▲ Source: Network
▲ Source: Taobao
First of all, the best water purifier is RO reverse osmosis pure water machine. Reverse osmosis is a process of separating water molecules from solutes by using the selective permeability of selective membranes that can only penetrate water but not solute. It can effectively filter bacteria, viruses, organic matter and heavy metals, remove residual chlorine and reach the standard of direct drinking.
Therefore, RO membrane is the core technology of water purifier, which is in the penultimate step. The purification step in the above picture can be directly passed by the water purifier without RO membrane.
Dow is the best RO membrane in America. Please make it clear when you buy it.
▏purifier▕ Water purification steps and principles
At present, most water purifiers on the market are five-stage filtration, and some of the latest models can reach six-stage filtration. At present, Xiaomi is still a four-stage filter.
In this regard, I also asked the shopping guide of the water purifier in the home appliance mall. The other party said that it is not possible to judge whether the filter is clean only from the series. American 3M water purifier can still ensure the cleanliness of water quality only through secondary filtration.
▲ Schematic diagram of filtering steps? Source: Taobao
▲ Source: Taobao
However, it is better to choose more series than less series at the same price.
The primary filtration is mostly PP cotton: filtering large particles such as sediment, colloid and fiber.
The secondary filtration is mostly activated carbon filter element, and some of them are ultrafiltration membrane: absorbing residual chlorine, small molecular organic matter, odor, abnormal color and so on.
The third stage of filtration is mostly ultrafiltration membrane filter element or PP cotton: to further absorb impurities and protect the next RO membrane filter element.
Four-stage filtration is RO membrane: filtering scale, heavy metals, bacteria and so on.
Most of the five-stage filtration is the post-activated carbon filter element: it can inhibit bacteria and improve the taste of water.
The materials or order of the first three steps of each brand will be different, which will not affect the filtering effect. Its purpose is to filter large particles of impurities in water and reduce the burden of RO membrane filtration, as long as the penultimate part is RO membrane!
Moreover, the five-stage filtration does not necessarily correspond to five filter elements, and some will be hidden inside the machine.
▲ Source: Taobao
99.9% of the shopping guides indicated that the unplugged filtering effect and experience would be poor. In fact, the whole filtration step is only the core step of water purification, and RO membrane needs electricity. Because the pore size of RO reverse osmosis filtration membrane is too small (0.00 1μm), the pressure of tap water can't "pass", so RO reverse osmosis water purifier must go through the pressurization process, which requires the use of supercharger, that is, electricity.
Moreover, RO reverse osmosis water purifier will produce a lot of "wastewater" (purified water) while producing purified water.
So do you dare to have a water purifier that doesn't consume electricity or waste water? Tell me where the waste water went.
Don't be fooled by such advertisements! At present, there is no technology without wastewater, only water purifiers with low wastewater rate.
So don't be influenced by advertisements. If you plan to install a water purifier at home, please reserve a socket under the kitchen. Nowadays, water purifiers are very small, so there must be enough space under the kitchen. Don't worry about this.
Where is the purified water? Single outlet or double outlet? ▕
Clean water is not equal to waste water.
Although pure water can't be drunk, it is still high-quality domestic water. After being filtered by PP cotton and granular activated carbon filter, impurities such as sediment, colloid and heavy metals in water have been removed, which can be used for washing clothes, flushing toilets, washing vegetables and watering flowers.
Clean water is nothing more than direct discharge and reception. Most water purifiers only produce water, and this purified water must have been drained away.
▲ Source: Taobao
The design of double outlet water is to keep clear water and save water. This original intention is of course good. However, it should be noted that you must choose a water purifier with double pipes and double outlets, that is, pure water and pure water take two different pipes. If it is a double outlet or a pipe, don't choose it. Pure water equals white filtration!
However, even if there are two pipes, the water will eventually flow to a faucet, so the two kinds of water still have overlapping pipes. If you still care, just choose a plain one.
In order to save water, choose a water purifier with high pure water ratio.
Waste water rate
▲ Source: Taobao
The wastewater rate of AO Smith's best water purifier can reach 3 cups of purified water (drinking water): 1 cup of purified water (domestic water), and the ordinary water purifier is 1 cup of purified water: 1 cup of purified water.
The angel's wastewater rate is 1- 1.5 cups of purified water: 1 cup of purified water.
The wastewater rate of millet is 1 cup of purified water: 1 cup of purified water.
Haier's wastewater rate is 1 cup of purified water: 1 cup of purified water.
The wastewater rate of Qinyuan is 2 cups of purified water: 1 cup of purified water.
In this way, AO Smith and Qinyuan have greater advantages, and there is no difference in others.
▏ Frequency of replacing filter element ▕
The replacement frequency of the filter element determines the subsequent cost of the water purifier.
How often to change this is related to the frequency of household use and the local water quality, and cannot be generalized. Just tell me what kind of water purifier you choose to reduce the cost of replacing the filter element.
1. It is better to buy multi-level indicator lights.
At present, most water purifiers on the market have indicator lights to indicate whether the filter element needs to be replaced. Those without indicator lights are old models, and it is not recommended to buy them.
With indicator light, it is also divided into one or more indicator lights.
▲ Source: Taobao
There is only one indicator light, and one of the five filters will light up when it needs to be replaced, and we don't know which one to replace at all, so we can only replace them all. PP cotton is usually replaced every 3-6 months. If it is better, it must be replaced every 6- 12 months, and the filter at the back takes longer.
When an indicator light is on, it may just be that PP cotton needs to be replaced, but we can only replace it all when it is uncertain, which not only wastes resources, but also wastes money.
The multi-indicator water purifier will clearly tell you which filter element needs to be replaced, which is very accurate.
It's better to buy one with cleaning function.
Some cheap or unwashed water purifiers can only replace the filter element according to the indicator light.
▲ Source: Taobao
Water purifiers with cleaning function are divided into automatic cleaning and manual cleaning.
Automatic cleaning is usually 72 hours, and the water purifier will automatically clean the filter element. Suitable for families who often cook at home and often use the kitchen.
Manual cleaning only needs to press the cleaning button manually. Suitable for low frequency use in kitchen.
Only Xiaomi can replace the filter by himself, and other brands need to be replaced by factory personnel.
▲ Source: Taobao
Here, I want to talk about the replacement of filter element by AO Smith.
AO Smith, each filter element corresponds to only one machine. In other words, the barcode of the new filter element that the factory staff got from the factory only corresponds to your water purifier. If the filter element is replaced in the middle, the water purifier will not work after installation, which fundamentally prevents manufacturers and staff from using the filter element to shoddy.
Because a whole cylindrical filter element was replaced, we can't tell whether the new filter element is new or old from the appearance.
AO Smith's filter replacement method is more reassuring. The shopping guides of other brands did not specify, but told me that the factory staff came to replace it.
Do you want a pressure bucket? ▕
▲ Source: Taobao
No pressure barrel is better!
All brands have non-pressure barrel and non-pressure barrel styles. It is best to choose a water purifier without pressure barrel. Water stored in it is easy to breed bacteria and cause secondary pollution. The non-pressure bucket ensures the water quality and saves the space under the kitchen.
5 brand personal feelings comprehensive evaluation
Finally, compare and recommend the above five brands, and know that everyone likes to watch this one best. But this is just my personal feeling and recommendation. Please look around and buy according to family needs.
Living in a model has nothing to do with all the brands below.
Ao Smith
The unique filter replacement technology makes me feel particularly at ease, and AO Smith is a big brand for many years and is a water heater at home. It has never had any problems after years of use. In the case of emotional foundation, this brand will be my first choice.
The disadvantage is that the price is higher, which is suitable for families with abundant budgets.
Recommended models: AOSmith 50D 1, AOSmith R400MTA 1(3: 1 wastewater rate, but expensive).
Purchase channel: home appliance mall or official flagship store of Tmall A.O. Smith
Qinyuan
As a water purifier, I want to say that I have heard of other brands, and Qinyuan is really the first time to hear of it. After understanding with the shopping guide of the home appliance mall, the brand Qinyuan was somewhat unexpected to me.
Qinyuan is the designated cooperative merchant for the 60th anniversary of the 2008 Olympic Games and National Day, and also cooperates with Vanke and China Resources Real Estate. It has the largest research base in Asia and numerous water purification awards at home and abroad. This year, it won the GWPS Water Purification Summit (the "Oscar" in the water purification industry) and the "Terez Excellent Product Award". The shopping guide also said that Qinyuan did not advertise for so many years.
Besides AO Smith, Qinyuan is my second choice. The honors and patents I have won are still attractive to me, and the price is moderate.
Recommended models: Qinyuan QR-RU-504A, Qinyuan QR-RU-05A, Qinyuan 502B (GWPS water purification summit GWPS award-winning products).
Purchase channel: Home Appliances Mall or Tmall Qinyuan flagship store.
Haier Group
Needless to say, Haier has a great mass base. But I personally feel that his water purifier products are not as good as other household appliances, and I personally don't recommend it.
The disadvantage is that the price is higher.
Recommended model: Haier 4H22
Purchase channel: home appliance mall (Tmall Haier flagship store has no water purifier, and other agents sell it).
angel
Personally, angels are neither bad nor bad. I have no reason to choose not to, and the price is moderate. Personally, Qinyuan at the same price is not recommended.
Recommended model: Angel j2577, Angel Pro.
Purchase channel: home appliance mall or flagship store of Tmall Angel water dispenser.
millet
Xiaomi's water purifier has two choices: kitchen top type and kitchen bottom type. The kitchen top type is suitable for families without reserved sockets under the kitchen. The price is cheap. I won't buy it first because I'm not a rice grain.
The disadvantage is that the kitchen style occupies the stage area.
Recommended model: kitchen top type or kitchen bottom type, depending on your family situation.
Purchase channel: Tmall Xiaomi official flagship store
▲ Source: Taobao
Many brands of water purifiers can be connected to mobile phones. For those who like to connect home appliances with mobile phones, Xiaomi is not the only choice.
The above five brands only focus on the fact that everyone will be affected by Taobao's sales ranking. In addition, there are other good water purifier brands, such as American 3M, Honeywell, Yikou and other brands.
According to the above precautions, choose a water purifier that suits your own situation and has the right price.
You can go to the appliance store to find out first, and then place an order online. After all, it's much cheaper to have activities online. Be sure to look for RO reverse osmosis membrane!
postscript
Many people think that the cost of replacing the filter element is still very high, which is not as good as the filter kettle in Birand.
I can only say that RO membrane does not exist in white! RO membrane can filter out the most difficult impurities such as heavy metals in water, which other filter elements can't reach!
Pure water is used for daily drinking, cooking and soup making. If you go to work during the day, you will lose one day. In this case, the filter element is still saved.
My family has been buying bottled water to drink, and everyone in the family goes to work, but there will still be cases where we can't continue drinking bottled water after drinking it. After learning about RO reverse osmosis pure water machine, I have planted grass and really plan to buy one for my family.
This answer comes from living well with users, many decoration strategies and home experience. Welcome to the Life Good APP.