一直在知乎潜水，从没任何欲望自己主动写小作文，但今天看各种净水器的文章，尤其看到有宝妈吹爆 RO (反渗透）净水器，我实在是忍不住了。
声明一，这里不作任何净水器推荐。这里只是希望大家不要迷信“纯净水”。
声明二，不反对净水器，以中国的水质，自来水不做处理直接饮用，还是有点玄。
水作为人体所需的自然资源，是含有人体所必需的有益矿物质的，且是其他食物资源无法补充的。所以并不是说，烧开水，壶底有水垢就是水不好。人的身体是需要这些矿物质的。如果用了一两个月的烧水壶，里面一点水垢都没有，你才需要担心，大大的担心！
RO 技术最早是在缺少淡水，或极端硬水的地方 （参见 TDS, total dissolvable solids ）采用的产水方式，真不是给普通大众用的。
早些年，（≫10年），在美国，也有一段流行RO, 出了不少吹爆 RO 的专业文章。但大家要知道，这是美国科技公司的管用营销手段，这些公司的科研部门的一部分工作就是写专业文章为自己的产品找到科学根据。但问题是，大众或媒体看到的只是这些人家要推的文章的内容，其实在真正的专业领域，还有好多其他的讨论，比如文章是否只分析了一部分数据，得出了基于不完整数据的部分判断，还需要更系统长期的研究，产生更全面的结论等。RO 早期的吹捧就源于此。
现实是，在美国，除非是特殊需求，绝大多数人不会单独使用 RO 纯净水，或其他形式的桶装 “纯净水” “蒸馏水” （是的，超市里有卖蒸馏水）。注意这种纯净水就是那种里面 TDS 趋近于零，大家追求的煮水无水垢的水。因为有益的矿物质都没了。儿科医生也会叮嘱不要用 RO, 还会根据孩子所在地的自来水厂，酌情考虑添加个别 TDS. 前面说“单独”饮用是说，讲究的人，还是用 RO, 但人家后面还要用矿物质添加器，把矿物质加回去啊。加回去以后，煮水会有水垢哦。但这种人工添加也不是很理想，不全面。
另一个现实是，关于长期饮用 RO 水对身体损害的文章，不要太多。长期是指>3个月，或更短。。。下面我贴一小段，懒得翻译了。有兴趣的可以上网翻翻。
Dangers of Reverse Osmosis (RO) water
Dangers of Reverse osmosis (RO) water
Consuming reverse osmosis (RO) water for even a few months can create serious side effects, warns WHO.
It has been scientifically confirmed that drinking reverse osmosis water causes more bodily harm and faster than most contaminants found in tap water.
Reverse Osmosis (RO) systems to purify water are in use extensively. Besides the aqua companies that market RO water personal water purifiers are also preferred by many households. RO system off course removes water impurities. But they also remove 92-99% of beneficial calcium and magnesium!
After analysing hundreds of scientific studies concerning RO water, the World Health Organization states that such water has a DeFinite adverse influence on the animal and human organism.
Side effects, even after just a few months
What is alarming is the fact that consuming RO water for even just a few months can create serious side effects.Czech and Slovak populations who used reverse osmosis water developed various health complaints suggestive of acute magnesium (and possibly calcium) deficiency within several weeks or months. Among the complaints were cardiovascular disorders, tiredness, weakness or muscular cramps.
Dietary minerals do not compensate the lack of minerals in RO water
RO water which doesn’t contain enough minerals, when consumed, leaches minerals from the body. This means that the minerals being consumed in food and vitamins are being urinated away. Less minerals consumed plus more minerals being excreted causes serious negative side effects and big health problems. In a scientific study performed to see if minerals consumed in food can make up for the lack of minerals in RO water, scientists concluded that reduced mineral intake from water was not compensated by their diets. Low-mineral water was responsible for an increased elimination of minerals from the body.
Negative effect on homeostasis mechanisms
Consumption of RO water leads to the dilution of the electrolytes dissolved in the body water. Inadequate body water redistribution between compartments may compromise the function of vital organs. Side effects at the very beginning of this condition include tiredness, weakness and headache; more severe symptoms are muscular cramps and impaired heart rate. Long-term consumption of acidic filtered water devoid of essential elements produced by RO filters is unhealthy.
Risk factor for many diseases
Recent studies suggest that RO water may be a risk factor for hypertension and coronary heart disease, gastric and duodenal ulcers, chronic gastritis, goitre, pregnancy complications and several complications in new-borns and infants, including jaundice, anaemia, fractures and growth disorders.
Use of RO water for cooking causes substantial losses of all essential elements
When used for cooking, RO water was found to cause substantial losses of all essential elements from food (vegetables, meat, cereals). Such losses may reach up to 60 % for magnesium and calcium or even more for some other micro-elements (e.g., copper 66 %, manganese 70 %, cobalt 86 %). In contrast, when mineralized water is used for cooking, the loss of these elements is much lower, and in some cases, even higher calcium content was reported in food as a result of cooking.
Addition of minerals to remineralise the RO water will not be optimum
According to the World Health Organization the practice of adding minerals back into the reverse osmosis water could not be considered optimum, since the water does not contain all of its beneficial components. In the case of borderline deficiency of a given element, even the relatively low intake of the element with drinking water may play a relevant protective role. It is practically impossible to recreate natural water with all of its minerals and trace elements from RO treated water.
Recent recommendations
More recent studies have provided additional information about minimum and optimum levels of minerals that should be available in demineralised water.
Magnesium- a minimum of 10 mg/L and an optimum of about 20-30 mg/L
Ccalcium- a minimum of 20 mg/L and an optimum of about 50 (40-80) mg/L
Total water hardness- the sum of calcium and magnesium should be 2 to 4 mmol/L
At these concentrations, minimum or no adverse health effects were observed.
Besides the adverse effects described above RO systems also waste 70-80 per cent of water during filtration. This ‘reject’ water is saline as it has a higher concentration of chemical contaminants and is of no use for any other purpose.
Alternative to RO systems
Boiling
Proper boiling must be ensured. Let the water steam and churn for a couple of minutes. However, the chemical contamination present in water is not completely eliminated by boiling. Furthermore, boiling may not always be possible anytime in any situation due to lack of heat source or shortage of fuel or electricity.
Chlorine
Pour four drops of liquid bleach in one liter of water; 8 drops in per half gallon; and 16 drops in per gallon of water. Let it rest for at least half an hour to make the water drinkable. Excessive chlorine can be dangerous to health and must maintain some caution.
Iodine
Pour 5 drops of iodine in per liter of clean water. Add some extra few drops if the water is cloudy. Let it rest for at least half an hour before it is Suitable to drink. Iodine is more effective if the water temperature is more than 21 degrees Celsius. However, iodine does not kill all 100% of the pathogens present in water. |
