Fact or fallacy: Is your water purifier safe?

Imagine a business that does not involve raw material cost and deals with a product that is in high demand. That is what the business of supplying RO water (or water purified through reverse osmosis) is like in Vidarbha region, says Vinod Lunge of Mangrulpir taluka in Maharashtra’s Washim district. Lunge used to work with a land development bank in Washim till 2011. After the bank shut shop, he decided to try his luck in the booming water purification market, and set up an RO plant at one corner of his orange orchard. “I invested Rs 4 lakh on setting up the plant along with a chiller machine and another Rs 3.5 lakh on buying a pick-up car for delivering water jars. The plant uses 12,000 litres of groundwater daily from a borewell in my farm and yields 4,000-4,500 litres of filtered water, which I supply to 380 households,” says Lunge, adding that he makes a profit of Rs 30,000 a month from the business.

Residents estimate that over the past decade more than a dozen RO-based water purification plants have sprung up in Mangrulpir. Sachin Kulkarni, a social activist from Washim district, explains the reason for the flourishing business: “People depending on groundwater find the taste brackish and unpalatable, while those who have access to tap water supplied by the municipality complain of a strong smell of chlorine and bitter taste.”

Halfway across the country in Haryana’s Charkhi Dadri district, Jai Bhagwan, a 60-year-old resident of Gothra village, also blames brackish groundwater and irregular water supply for the mushrooming RO plants in the region. He buys a 20-litre water jar every other day from an RO plant in neighbouring village. In Uttar Pradesh’s Shravasti district, Virendra Mishra has set up an RO plant in his farm land in Patna Khargaura village. He claims that the district has 75 RO plants. Located just 4 km from the district headquarter of Bhinga, most households in the village have access to tap water. “But it usually has a yellow tint. So people have started buying RO water for drinking purposes,” says Rahul Pandey, a resident of Patna Khargaura.

A report “Water Purifiers for Drinking Water” published by the National Institute of Hydrology in Roorkee, Uttarakhand, says that yellowness in water is a sign of excess iron or bacterial infection, which can be eliminated by simply boiling water. However, Rahul says there is a firm belief among residents in the village that the RO water is better for health.

Such belief also appears to be driving up the market of point-of-use domestic RO systems, particularly in urban areas. In 2018, when 45-year-old Rakesh Parmar shifted to his new house in Greater Noida, in the National Capital Region (NCR) of Delhi, he immediately installed an RO system and discarded his carbon-candle water purifier. His housing society receives groundwater and Parmar finds the taste and odour of the water quite palatable. His decision was purely based the suggestion of his neighbours who believe that the region’s groundwater is contaminated with heavy metals. Santosh Kumar Jha, an RO trader from Delhi, tells Down To Earth (DTE) that Delhi-NCR accounts for 70 per cent of the RO sold in the country.

According to a 2017 report by Transparency Market Research, a market intelligence company in Pune, of the various water purifier technologies available in India, RO technology has the maximum 37 per cent market share. This share is only going to go up as the country’s water purifier market is poised to double—from US $3,080.7 million in 2023 to $6,880.3 million by 2032, as per the “India Water Purifier Market Report” by International Market Analysis Research and Consulting Group (IMARC) Group, a market research firm. Though the market is currently dominated by industry behemoths like Eureka Forbes, Kent RO Systems, Hindustan Unilever, Tata Chemicals, Ion Exchange, Blue Star, AO Smith Corporation, Livpure, LG Corporation and Nasaka, the competition is likely to get stiff due to the introduction of several small and local players.

However, DTE analysis shows that RO water purification business is shrouded in mystery—little is known about the effects of RO water on people’s health and about regulations that govern the industry.

Quest for clean water

Various methods, technologies to remove impurities from water

Purity for taste or health?

Water is not merely the combination of hydrogen and oxygen. Depending on its origin and flow path, it contains a number of particles, including microscopic organisms like certain bacteria that are beneficial to our health. Water also contains small amounts of essential minerals like calcium and magnesium that aid in the development of muscles, heart function and production of enzymes, along with sodium, potassium, copper, iron and zinc, says a chapter in the 2021 book Climate Impacts on Water Resources in India, written by researchers led by Rajesh Singh from the National Institute of Hydrology in Roorkee. When passing through polluted areas, water becomes the carrier for disease-causing microbes and fertiliser runoff like ammonia and pesticides. At places, groundwater may contain elements like fluorides and heavy metals like chromium, arsenic and lead, which if ingested in larger amounts, can lead to anaemia, liver and kidney ailments and even increase the risk of cancer. The load of minerals and heavy metals in water is called total dissolved solids (TDS)—a high TDS level is usually responsible for the unpalatable taste and hardness of water.

Among all the water purification systems, RO is fast gaining popularity as it can not only remove impurities and pathogens but also lower the TDS level. A typical RO system consists of a semi permeable membrane, with pores 0.0001 to 0.001 microns in size. As untreated water passes through the membrane under applied external pressure, dissolved salts, impurities and germs are separated—thus providing water that is clean and sweet.

RO systems come with the claim to remove 90-100 per cent of TDS, says Anil Arora, senior consultant at the Institute of Liver Gastroenterology and Pancreatico Biliary Sciences, Sir Ganga Ram Hospital, New Delhi. But in this process, essential minerals like calcium and magnesium are also lost. This could pose a public health threat as most people in the country suffer from micronutrient deficiency, says Arora. He calls for an in-depth study to understand the effects of RO water on health.

In the report “Water Purifiers for Drinking Water”, the researchers from the National Institute of Hydrology in Roorkee tested three brands (names withheld) of RO water and found that in two of them, TDS was less than 50 mg per litre (mg/l). Physiochemical analysis indicated decreased calcium and magnesium levels.

Atul V Maldhure, principal scientist at the Council of Scientific and Industrial Research-National Environmental Engineering Research Institute (CSIR-NEERI) tells DTE that in almost 4,000 places across the country, he has tested the quality of RO water installed in households, and has found the TDS in the range of 25 or 30 mg/l. Such low level of TDS indicates low levels of essential minerals in water.

The Society of Pollution and Environment Conservation Scientists (SPECS), a non- governmental organisation based in Dehradun, has been examining water sources in the city for the past two decades. Brij Mohan Sharma of SPECS tells DTE that in many areas drip candle filters are sufficient to purify water, but due to a huge lack of awareness, people race to install RO systems. Sharma says that in most houses surveyed by SPECS, RO water has TDS of 18 to 25 mg/l. “This is dead water. It can be used in batteries but not for drinking.”

In a bid to regulate the use of RO purifiers, the National Green Tribunal (NGT) in May 2019, directed the Union environment ministry to issue notification, prohibiting the use of RO where TDS in water is less than 500 mg/l, and wherever RO is permitted, a requirement is laid down for more than 60 per cent recovery of water. The NGT order was based on the report of an expert committee which said that if TDS is less than 500 mg/l, an RO system will not be useful but will result in removing important minerals as well as cause undue wastage of water. In March 2022, the Supreme Court stayed the NGT order, which was challenged by the Water Quality India Association, a non-profit in Mumbai.

In November 2023, the Union environment ministry published the Water Purification System (Regulation of Use) Rules, 2023, which outline guidelines for the proper management, storage, and utilisation of reject water and discarded elements generated by these systems. “The notification has given one year to RO companies to abide by the rules. The notification also ignores the NGT recommendation to keep the minimum TDS level at 150 mg/l,” says Sharad Tiwari, founder of Friends, a non-profit, which had approached NGT, seeking conservation of potable water by preventing its wastage on account of unnecessary use of RO systems.

In January, DTE filed a Right To Information (RTI) application with five questions for the Indian Council of Medical Research (ICMR): Does the drinking water coming out of RO system have any adverse effect on health? Is there mineral deficiency in the drinking water released from RO? If yes, then what kind of mineral deficiency is observed in the body? The third question was, has any study been done on the effects or side effects of RO water on the body, if yes, can the report be shared? The fourth question was whether RO water has been recommended by the Union health ministry for villages, cities and towns, and finally, whether there is any research on the impact of RO systems on public health.

On February 21, ICMR-National Institute of Nutrition, Hyderabad, gave a single-sentence answer to the questions: “We do not have this information.”

This article was originally published as part of  Down To Earth’s special issue dated 16-31 March, 2024.  Download the full story for free

Earlier, in August 2023, a study published in Journal of the Indian Medical Association by researchers from the Medical College Baroda in Vadodara, says 90-92 per cent of beneficial calcium and magnesium are removed by RO systems. The study analysed the health condition of more than 2,600 urban citizens of Vadodara and found a “statistically significant association between RO water usage and joint pain”. The research also explored a link between RO water and coronary heart disease and back pain, but found no correlation. Its results, however, are preliminary, and it emphasises that more analysis is needed.

Another study in Vadodara, published in The Egyptian Journal of Internal Medicine in January 2022, says RO water also causes deficiency of micronutrients. It analyses patients visiting SSG hospital (Sir Sayajirao General hospital) in the city in 2017-18 with symptoms of vitamin B12 deficiency. The results significant association of vegetarian diet, dark complexion, socio-economic status and use of RO water with vitamin B12 deficiency. However, it notes that the results cannot be generalised.

Similar impacts have been reported from other parts of the world. In a 2005 paper, the World Health Organization (WHO) highlights cases in the Czech and Slovak populations who began using RO systems in home taps in 2000-02. Within months, the populations complained of cardiovascular disorders, tiredness, weakness or muscular cramps—this indicates acute magnesium (and possibly calcium) deficiency, notes the WHO paper.

Rajesh Singh from the National Institute of Hydrology explains another way water with low TDS can harm health. “Water with low TDS is called ‘hungry water’. Drinking two glasses of such water will not make any immediate difference but will gradually absorb the enzymes and minerals already present in the body. This can cause problems like diarrhoea.”

Too high or too low?

In its drinking water standards issued in 2017, WHO states that TDS in drinking water should be between 600 and 1,000 mg/l. However, it acknowledges that there is little data on whether excess or low TDS has any adverse health effects. Countries in Europe, the US and Canada have set TDS standards at 500 to 600 mg/l. In India, the Bureau of Indian Standards (BIS) has set standards for drinking water since 1991. According to its latest norms in 2012, maximum limit of TDS should be 500 mg/l. However, in the absence of any alternative water source, a TDS limit of 2,000 mg/l is permissible.

To address concerns related to TDS, RO manufacturers introduced TDS controllers (or modulators) and mineral infusion cartridges (or mineralisers) for commercial and residential machines. TDS controllers help set TDS levels in purified water, while mineral cartridges inside the machine infuse specific minerals into water as it passes.

Reduction of TDS also lowers pH, which increases the acidity of water. Hence, newer RO systems have alkaline cartridges so compounds like bicarbonates and hydrogen oxide can be infused. While little is known about the beneficial impacts of the TDS controllers, mineral and alkaline cartridges, such “superior technologies” have definitely helped companies keep the prices of their RO elevated.

Take Kent, a major RO player, which has four wall-mountable RO systems under the label “Elegant”. The Kent Elegant Lite, whose features read as “RO+UF+TDS Control”, retails for Rs 21,000 (UF stands for ultra filtration, an RO-like method of purification). The Kent Elegant Alkaline (RO+UF+TDS Control+Alkaline +UV In-tank) and Elegant Copper (RO +UF+TDS Control+Copper+UV In-tank) are priced at Rs 21,500 each, while the Kent Elegant RO purifier (RO+UF+TDS Control+UV In-tank) sells for Rs 22,000.

Similarly, Livpure has a Zinger Water Purifier with RO+UV+UF technology and a copper 29 cartridge for Rs 20,990, and a similar system for hot water for Rs 31,990. The company also has multi-filter alkaline system, Envy, for Rs 21,490. These systems also incur recurring expenses as filters, the RO membrane and cartridges need to be periodically changed.

The RO industry may be due for one new technology, with BIS’S new standards, IS 16240, issued in 2023. According to BIS’s response to an RTI application filed by DTE, the new standards allow addition of minerals in ROs producing 50 litres per hour. Scrutiny of the claims made by RO companies for BIS standard licences shows that no one has so far mentioned artificial addition of minerals to the water.

To understand whether RO water is scrutinised, DTE in January filed an RTI application with various authorities such as the Union health, environment and drinking water ministries, the Central Pollution Control Board (CPCB) and the Delhi Jal Board, asking if the output of domestic RO firms is tested. Only CPCB responded as of March 4, saying that testing the water does not fall within its ambit.

Focus on toxins

“It is a myth that RO is the solution to all water problems,” says Ashok Ghosh, chairperson of Mahavir Cancer Sansthan & Research Centre, Patna and former chair of the Bihar State Pollution Control Board. “Most ROs claim that they have installed a mineraliser, but there is no clarity on how much this increases or decreases the mineral level,” he says. 

Even if minerals in water could be tested, they are likely not enough to meet humans’ requirement. Rajesh Singh of the National Institute of Hydrology explains that this plays back to a scientific debate on whether water should be considered a source of minerals. “Humans get minerals less from water and more from grains and vegetables. The calcium requirement of an adult human being is fulfilled by two glasses of milk. This is also the reason WHO has not given much importance to the health effects of TDS in water,” he says.

Experts highlight that when assessing the need for RO, emphasis should be on the region and the condition of water. The “Water Purifiers for Drinking Water” report recommends that RO is only necessary in areas where the surface or groundwater is hard. In many places where surface water is the source of drinking water, a combination of candles, activated carbon and UV filters is sufficient for water purification.

BIS, in its 2015 standards IS 16240, cautioned that RO systems cannot be recommended for areas where arsenic level is above 0.1 mg/l and fluoride is more than 8.0 mg/l. This has, however, been excluded from updated standards in 2023.

Recently, NGT has taken suo motu cognisance of the issue of arsenic and fluoride in groundwater in various areas of the country. NGT, on the basis of a report, found that arsenic is present in 230 districts in 25 states of the country, while there is a problem of fluoride in 469 districts of 27 states. But the Central Ground Water Authority has not installed arsenic and fluoride removal plants in these areas.

“RO definitely rejects arsenic and fluoride, but if the problem is only of these toxic elements, then we should use selected technology to remove them. For example, in places like Jharkhand and Odisha, people still use hand pumps where there is a problem of arsenic or fluoride. But as soon as water reaches every house through pipes, it will be the responsibility of the corporation or panchayat to supply water as per BIS standards. In such a situation there should be no need for RO,” says Maldhuru of CSIR-NEERI.

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