Is it Safe to Drink RO Purified Water?

Safe RO Purified Water

In recent years, RO purified water has become very popular. Today, you see a RO water purifier in almost everyone’s kitchen. But do all of us really need them?  Isn’t a good UV water purifier with pre filter, activated carbon cartridge and UF cartridge enough for most households?

To add to this, a recent WHO study on health effects of drinking demineralised water has raised questions about the safety of drinking RO water on human health over long term. Modern RO water purifiers do come with a mineralizer to balance PH and minerals in purified water. But is that enough to fix this issue?

In this article we will list the risks and benefits of a RO water purifier. We will discuss the findings of the WHO report and also find an alternative water purification solution that could be an effective and safe solution.

Lets Start…

What is Reverse Osmosis?

Reverse Osmosis or R.O. is a water purification method that uses a semi-permeable membrane and pressure to remove dissolved salts (ions), micro organisms, and other impurities from drinking water. The purified water obtained after this process is as good as distilled water and is almost completely de-mineralized water.

A reverse osmosis system can remove not just micro organisms but also dissolved salts like sodium, calcium, magnesium, bicarbonate, lead, arsenic, copper, chromium, selenium, fluoride, radium, barium, cadmium, nitrates and nitrites from the water.

Why are RO water Purifiers Gaining Popularity?

RO water purifiers are incredibly popular for several reasons reasons.

  1. Most Effective Solution: These filters are best at removing a large number of contaminants out of the water, including bacteria, virus, certain pesticides, chemicals, and minerals.RO water is as safe as distilled water.
  2. No More Water Borne Diseases: RO water protects us from diarrhea, Jaundice, and other water born diseases.  This effect on health is noticeable immediately.
  3. One Solution for All: Ideally, people should check chemical composition and TDS of water before deciding on the type of water purifier best for them. However, most people skip this step and buy a RO purifier thinking it to be the best solution for all types of water.
  4. Social Status: Many people buy a R.O. water purifier because guests visiting them ask for R.O. water. Some even ask questions like “Don’t you have a RO Purifier? !!!”
  5. Follow the Trend: Many people don’t even care to know about the type of water purifiers available and will just buy a RO purifier because everybody else is buying it. Follow the crowd (Bheed Chal)
  6. Affordability: RO water purifiers have increasingly become more and more affordable. Today one can buy a good RO water purifier from $100 and above. In countries like India one can buy RO water purifier under 10,000 rupees. Some local brands sell RO water purifier for as low as 5000 rupees.

Is RO Purified Water Safe to Drink?

The question about safety of drinking RO purified water became headlines after WHO published results of its study in report “Health Risk From Drinking Demineralized Water – W.H.O.“.

Under conclusion of this report, the author writes:

Sufficient evidence is now available to confirm the health consequences from drinking water deficient in calcium or magnesium. Many studies show that higher water magnesium is related to decreased risks for CVD and especially for sudden death from CVD. Recent studies suggest that the intake of soft water, i.e. water low in calcium, is associated with a higher risk of fracture in children, certain neurodegenerative159 diseases, pre-term birth and low weight at birth and some types of cancer.

This report recommends re-mineralisation of RO water to make it safer. but also notes that..

Possibly none of the commonly used ways of re-mineralization could be considered optimum, since the water does not contain all of its beneficial components. Current methods of stabilization are primarily intended to decrease the corrosive effects of demineralised water.

Re-Mineralization Cartridge – Does it Fix the Problem with RO Water?

After this WHO report, there has been a trend of creating artificial alkaline water or ionized water to fix the de-mineralized and acidic RO water.

However, I feel that it is still more safer to drink natural alkaline water than any kind of artificial water. Artificial alkaline water doesn’t have the natural concentrations of the different substances found in spring water.

Natural water that passes through rocks and soil will always pick up minerals and other substances. These substances are essential for the protection and healthy functioning of the body.

Distilled water or RO purified water may be safe but it doesn’t hydrate your body or help the body in protecting itself.

Drinking water should contain minimum levels of certain essential minerals (and other components such as carbonates). Unfortunately, over the two past decades, little research attention has been given to the beneficial or protective effects of drinking water substances.

The text above is from the WHO report on effects of drinking de-mineralized water. The use of word “substances” instead of minerals is interesting here. Because natural water not just contains minerals but also bicarbonates, trace elements, and other substances that are beneficial to our bodies. All of these are removed in RO purification and once removed, no re-mineralization method could be considered optimum.

Which Water Purifier is Ideal for Your Home?

Before selecting a suitable type of best water purifier, you must first understand the chemistry of water at your home. The least you should do is buy a TDS meter and find out the TDS content of water at your home.

TDS or Total dissolved solids is minerals, salts or and some organic matter dissolved in water. The solids dissolved in water can be iron, chlorides, sulfates, calcium or other minerals found on the earth’s surface.

 According to WHO, the water with a TDS level of less than 600 mg/litre is considered to be good. As per IS 10500 (drinking water) the TDS should be less than 500.  


So, we can conclude that if the TDS test of your water shows TDS count of less than 500 mg/litre, then you simply don’t need a RO water purifier. Look for a simple water filter and that will not just protect you from diseases but also save you money. A good choice would be a UV Purifier with sediment filter and activated carbon post filter.

If the TDS count is above 500mg/litre, then you have no choice but to go for a RO water purifier. In this case make sure that you buy a RO water Purifier with a mineralizer that adds several minerals in water and not just calcium and magnesium. If your RO water purifier comes with a TDS Controller, then you can adjust the TDS in purified water as per your choice. We recommend it to be 100 – 150 mg/liter

If the source water at your home is polluted with heavy metals, or tastes bad, then irrespective of TDS of input water, you would still need to use a RO water purifier with a mineral cartridge. Mineral cartridge is necessary here to keep the water alkaline and with ideal TDS in RO water.

In this case I would advise avoiding RO water purifiers that come with TDS controller as they pass some percentage of water directly to UV or UF filter without passing through RO membrane.


RO water, when sufficiently mineralized with a good mineral cartridge is probably safe for human consumption. I used the word “probably” because there isn’t sufficient research or evidence available about safety of drinking artificially mineralized RO water over long term.

But if you ask me which type of water is the best, then it is UV filtered tap or ground water without a doubt. You just need to be living at a place where the quality of input water is not too poor. However, this is not an option for most of us and hence the popularity of RO water purifiers.

Riya Menon
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