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Reverse osmosis is a highly effective technology for purifying drinking water, capable of removing a wide range of contaminants. However, the reduction in essential minerals necessitates remineralization to ensure the water is both safe and palatable. While RO-purified water is generally safe to drink, attention must be paid to its mineral content to avoid potential health risks. Further research and standardization of RO systems for domestic use are essential to optimize the safety and quality of drinking water.
Reverse osmosis (RO) is a widely used water purification technology that employs a semipermeable membrane to remove ions, molecules, and larger particles from drinking water. Given the increasing concerns about water pollution and the need for safe drinking water, the application of RO has gained significant attention. This article explores the safety of drinking water purified by reverse osmosis, examining its effectiveness in removing contaminants, the impact on mineral content, and potential health implications.
Effectiveness in Removing Contaminants
Reverse osmosis is highly effective in removing a wide range of contaminants from drinking water. Studies have shown that RO can significantly reduce the presence of polar organic micropollutants, arsenic, and other harmful chemicals. For instance, a pilot-scale study demonstrated that RO could remove up to 99% of arsenic from groundwater, making the water compliant with WHO and National Indian Standards2. Another study highlighted the robustness of RO in removing polar organic micropollutants, with passage figures ranging from less than 1% to 25%1.
Impact on Mineral Content
While RO is effective in removing contaminants, it also reduces the mineral content of the water. This can have both positive and negative implications. On the one hand, the removal of harmful inorganic minerals is beneficial. On the other hand, the reduction of essential minerals such as calcium and magnesium can affect the taste and potentially lead to health issues. Research has shown that remineralization of RO water can improve its sensory quality and make it more acceptable to consumers4. However, the low mineral content in RO water has been associated with health hazards such as dental caries and cardiovascular diseases7.
Health Implications
The health implications of drinking RO-purified water are a subject of ongoing research. While RO effectively removes harmful contaminants, the reduction in essential minerals can pose risks. A study comparing RO-processed and unprocessed water found that RO water had significantly lower levels of total dissolved solids (TDS), hardness, and fluoride, which were associated with a higher incidence of dental caries and cardiovascular diseases7. Therefore, it is crucial to ensure that RO water is remineralized to meet the required standards for safe drinking water.
Is reverse osmosis purified water safe to drink?
Marjolein Vanoppen has answered Near Certain
An expert from Ghent University in Environmental Engineering, Clean Technology, Environmental Science
RO water is actually ‘to clean’ to drink, and minerals/salts should be added especially if this is the main source of drinking water. In the same way seawater contains too much salt to be healthy, RO water can contain too little.
Is reverse osmosis purified water safe to drink?
Nicholas A Hoenich has answered Likely
An expert from Newcastle University in Mechanical Engineering
Reverse osmosis (RO) is a water purification method whereby water is forced through a porus membrane under high pressure. Up to 99% of the dissolved salts (ions), particles, colloids, organics, bacteria and pyrogens from the water entering the RO module are removed as the membrane rejects contaminants based on their size and charge.
Any contaminant with a molecular weight greater than 300 daltons is likely rejected by the membrane. Likewise, the greater the ionic charge of the contaminant, the more likely it will be unable to pass through the RO membrane.
Reverse osmosis is used in industrial settings, in the brewing industry ( to produce alcohol free beer) and in semiconductor manufacturing. It is also used to treat water used in the treatment of patients with kidney failure ( renal dialysis ).
Drinking water provided to household by a water utility company, via a pipe network, meets the legal requirements for drinking water in respect of the level of contaminants that it contains. Such water is also considered to be wholesome, meaning is fit to use for drinking, cooking, food preparation or washing without any potential danger to human health.
Compliance with such requirements is mandatory. Exceptions to this may be when the water is supplied from an artesian well such as in the case of isolated rural dwellings.
Within the US, limits for contaminants are set by the Environmental Protection Agency (EPA) and compliance is via the Safe Drinking Water Act, the equivalent in Europe is the Drinking Water Directive, which is translated into national regulatory requirements. The underlying scientific basis for these requirements can be found in the World Health Organisation ( WHO) guidelines for drinking water, which is the basis for drinking water requirements outside US and Europe.
Decisions to treat drinking water by Reverse Osmosis differ; it may be driven by local circumstances, such as the presence of industrial contaminants pesticides and herbicides, the need to treat water in emergency situations, such as following floods. It may also be used to provide water suitable for drinking in conflict zones.
Health risks associated with long term use of such water include:
a) Direct effects on the intestinal mucous membrane, metabolism and mineral homeostasis or other body functions.
RO water can have negative taste characteristics to which the consumer may adapt with time. RO water is also reported to be less thirst quenching, leading to excessive water intake. RO water also has negative effects on homeostasis mechanisms, compromising the mineral and water metabolism in the body. In simple terms, fluid movement across body compartments, and also in the elimination of fluid, it is not just fluid, but also electrolytes that are involved. The adequate intake of electrolytes is essential to minimize losses and maintain homeostasis.
b) Reduced intake of calcium and magnesium.
Calcium and magnesium are both essential elements. Calcium is a substantial component of bones and teeth. In addition, it plays a role in neuromuscular excitability (i.e., decreases it), the proper function of the conducting myocardial system, heart and muscle contractility, intracellular information transmission and the coagulability of blood. Magnesium plays an important role as a co-factor and is an activator numerous enzymatic reactions including glycolysis, ATP metabolism, transport of elements such as sodium, potassium, and calcium through cell membranes, synthesis of proteins and nucleic acids, neuromuscular excitability and muscle contraction.
Although drinking water is not the major source of calcium and magnesium intake, the health significance of supplemental intake of these elements from drinking water may outweigh its nutritional contribution expressed as the proportion of the total daily intake of these elements.
c) Reduced intake of essential elements and microelements.
Although drinking water, with some rare exceptions, is not the major source of essential elements for humans, its contribution may be important for several reasons. The modern diet of many people may not be an adequate source of minerals and microelements. In the case of borderline deficiency of a given element, even the relatively low intake of the element with drinking water may play a protective role. This is because the elements are usually present in water as free ions and therefore, are more readily absorbed from water compared to food where they are mostly bound to other substances.
d) The loss of calcium, magnesium and other essential elements from food prepared in RO treated water.
When used for cooking, in contrast to hard water substantial losses of all essential elements from food can occur. Since most nutrients are ingested with food, the use of RO treated water for cooking and processing food can cause a marked deficiency in total intake of some essential elements.
e) Impact of RO water on water distribution system
Higher leaching of metals from materials in contact with RO treated water such as brass fittings, lead piping and soldered joints results in an increased metal content of the water at consumers taps.
f) Impact on fluoride
Fluoride in drinking water may occur naturally, or be added, to control dental caries. Such fluoride will be removed by RO, removing the protection offered by the added fluoride.
In summary, the quality of water supplied through public water mains is strictly controlled by legislation to ensure that it is wholesome, and is also subject to regular testing to ensure that there is no loss of quality during transmission and storage. Such water contains
essential minerals and trace elements. The removal of these through RO, reduces these levels, and prolonged intake of RO treated water is likely to result in health consequences unless, attention is paid to ensure that potential body depletion is reversed.
If the rationale for treating water is to improve taste by the removal of disinfectant residues carbon filtration should be used. Carbon filtration will also remove inorganic compounds present in drinking water.
Is reverse osmosis purified water safe to drink?
Marta I Litter has answered Unlikely
An expert from University of San Martin in Environmental Science, Chemical Engineering
As salt components are removed by the process, the water will be not drinkable.