Is RO Water Harmful? Good For Health? Safe to Drink?

RO or Reverse Osmosis is the popularly followed water filtration method used in houses, industries, and city water treatment plants to remove the harmful minerals present in the source water to make it fit for human consumption.

This method involves the use of a semi-permeable membrane through which water is forced at high pressure. As a result, the heavy minerals with molecular weight above 20 do not pass through the membrane and get eliminated as wastewater. The resultant water is thus free of TDS and demineralized. Thus, one can call it nearly 100% pure.

Is RO Water healthy for consumption?

Now the question is whether this RO purified water is ideal for drinking. Though RO purified water is desalinated and demineralized, it is not the best for consumption because of various reasons. First, this water requires retreatment with specific mineral content to make it healthy for consumption.

WHO recommended that the minimum TDS levels in drinking water should be 100 mg/L. However, the optimum TDS levels should be 200 to 400 mg/L for chloride/sulfate waters and 250 to 500 mg/L for bicarbonate waters.

TDS in water

It is also recommended that the minimum calcium levels in desalinated water should be 30 mg/L. Increasing the calcium levels to 30 mg/L reduces the corrosive activity of desalinated water.

Thus, we can infer that consuming demineralized water is not advisable for our health. It needs to have specific levels of TDS for the water to be certified fit for human consumption. The WHO 2017 Report states that the palatability of water with TDS levels up to 600 mg/L is considered good for consumption.

Why is RO purification necessary?

Compared to other water filtration methods, RO water purification can remove more than 90% of minerals from the source water. However, it includes lead, arsenic

Simultaneously, one cannot discount the fact that the RO filtration process also removes essential minerals. However, water is not the prime source of essential minerals for our bodies. There are alternatives in the form of food we consume, dietary supplements, fruits, vegetables, meat, eggs, etc.

However, RO purification ensures to removal of 90% of the most toxic chemicals from the water that could cause serious damage in the form of long-term health risks. Nevertheless, the lack of essential minerals like calcium and magnesium in RO-purified water entails that your body does not get all the beneficial minerals it requires for healthy growth.

The ideal solution would be to eliminate harmful chemicals like arsenic, lead, cadmium, and others, while retaining essential chemicals like calcium, magnesium, potassium, sodium, etc.

Hence, you find RO water purifiers coming with TDS controllers and mineralizers that replenish the lost minerals and increase the pH value of water above 7 to make it fit and tasty for consumption.

TDS Controller in RO Water Purifier

As a result, you have RO purified water with all the essential minerals. They enhance the TDS levels of RO purified water to the levels specified by WHO to make it fit for human consumption.


We cannot say that RO water is entirely harmful to health. Yes, it does not contain essential minerals, but it also does not have harmful chemicals that could otherwise prove dangerous for human health.     

The ideal solution is to have a balanced TDS level by enhancing the TDS levels of RO-purified water after its RO purification process. The use of remineralization filters can provide solutions to a certain extent alone.

Dr Sandeep Raj
Dr Sandeep Raj
Dr. Sandeep Raj Bharma is a Pulmonologist and Sleep Specialist. He got International fellowship in sleep medicine in sleep medicine in 2010 and he is a member of american academy of sleep medicine. He did his MD in Pulmonary Medicine from Kamineni Institute of Medical Sciences, At kitchenarena he offers expert advice and oversees content creation concerning sleep and bedding topics.


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