India’s water crisis is becoming more acute every year. Most major cities will run out of groundwater by next year and clean drinking water, a basic necessity, will become scarcer in coming times.
While the government has said it is committed to supplying piped water to all households in the next five years, the quality of water supplied to homes has always been a concern. This also explains why many homes in urban India are now increasingly dependent on water purifiers using technology like RO (Reserve Osmosis), UV (Ultraviolet filtration), UF (Ultrafiltration) or a combination of all three.
But finding the right water purifier in India can be confusing. One major concern with RO water purifiers is that there is a lot of wastage of water, often up to 80 per cent. Further, many homes do not really need an RO, because the Total Dissolved Solids (TDS) levels are already within an acceptable range, and the water quality is clean with just some filtration needed.
TDS, bacteria and other risks
According to the World Health Organisation guidelines for drinking water, TDS principally includes calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates, and small amounts of organic matter in water. TDS can originate from natural sources or even sewage, according to the WHO.
India’s own standards for drinking water state that up to 500 milligram per litre (MG/L) is considered acceptable, though 2000 mg/litre would be acceptable when there is no other source available.
If one were to rely on borewell or tankers for waters, TDS levels tend to be higher. TDS levels greater than 1000 mg/litre make drinking-water increasingly unpalatable, according to the WHO.
There are other risks in the water such as presence of chemicals like chlorine or bleach along with bacteria and viruses, which one wants removed during the water purification process.
“Apart from TDS and other microbiological contaminants like bacteria, viruses, protozoa, cysts, etc, there are four major impurities present in water such as microplastics, pharmaceutical compounds and antibiotic residue. Other contaminants like lead, arsenic, nitrates and iron are specific to certain geographies in India,” explained Shashank Sinha, Chief Transformation Officer, Eureka Forbes Limited to indianexpress.com in an email.
He added: “There is no one size-fits-all solution that can be adopted to purify water. It is important to understand the water quality and accordingly decide on the purifier.”
Dr Mahesh Gupta CMD at Kent RO, in a telephonic conversation, said, “TDS is not at all desirable in the water. Yes, the minimum limit is up to 500, but when the technology exists, why should you take the chance when you can remove that.” “Chlorine needs to be removed as well,” he said, adding, “It is put by the civic bodies to ensure water does not develop bacteria. It is not a desirable element in high quantities.”
While Gupta believes that RO is a must for all and one should ideally avoid TDS, Sinha has a different view. “Research validates that if one uses RO water purification in areas where it is not required, then it leads not only to ‘demineralised water’ but also adds to water wastage. Reverse Osmosis is meant to remove high TDS (salt content), certain heavy metals and contaminants which are found in ‘few’ locations, not all,” he explained.
How to check for TDS, other impurities at home
The first step to choosing a water purifier would be to check TDS levels in your home. Basic kits to check for TDS to more complicated ones that can test for levels of lead, chlorine are available online. Still a basic TDS meter though will give you an assessment of the quality of water supplied to your home.
“Generally, water supplied from lakes, rivers, and harvested rainwater has a lower concentration of TDS, whereas the water drawn from bore wells or supplied by tankers has a higher concentration of TDS and other harmful chemicals. Choose a water purifier that can remove the new-age contaminants,” Sinha adds.
Check the specifications and the TDS range for which the water purifier is recommended. Website of popular brands like Aquaguard, Kent RO, AOSmith, all mention the TDS levels and water source for which the purifier is suited and ideally one must corroborate before hitting click and buy. For instance if you have municipal water, an RO might not be needed at all. For those using bore wells or mixed source, an RO+UV+UF technologies could make sense.
Water purifiers which have just UV+UF purification can get rid of most bacteria, viruses. These are suited for TDS range with 1 to 200 mg litre. Brands will also mention if the purifier should be used in those parts where the water supply is brackish, and it is best to double check all of these factors.
Water wastage with RO
For some homes, there is no other option but an RO because the water has very high TDS content or is just too brackish or has a strong odour. But that should not necessarily mean wastage of water as companies are now supplying options to store this rejected water.
“Kent supplies RO with no water wastage. We have ROs with two tanks, one with the pure water, the other keeps on collecting the rejected water. The water can be used for washing used utensils, mopping the floor. At the end of the day, you have the option of not wasting any water,” Sharma explained. He also says the cost of these ROs, which have the option of saving water is not significantly higher.
“The RO method filters impurities using a membrane technology but in turn requires additional water to clean the filter. There is water wastage depending upon the model of the purification unit. There is also Green RO water purifiers, which reduces water wastage. These water purifiers are best suited for water sources with TDS (total dissolvable solids) levels ranging from 200 to 500ppm,” Sinha wrote.
In short, even if you have an RO at home, there are ways to reuse that water and ensure that it does not go down the drain.
Stainless steel storage
Some water purifiers now also tout stainless steel storage options, which can push up the cost further. The assumption being that the plastic storage tank inside the purifier is not ideal. But as Sharma points out these are not really needed. “We don’t believe in those systems. Once water is purified, and stored it is good enough,” he says.
Electricity or not electricity
With water purifiers, there are cheaper non-electric versions as well. Non-electric water purifiers will remove impurities as well depending on the technology being used. Some offer UF technology, sediment filtration as well as carbon filtration to remove odour and smell and Chlorine.
“However, what also needs to be kept in mind is that an electric water purifier can be useless in areas where electricity and running water are not available. Depending upon the need, one can choose from electric and non-electric water purifier available in the market,” Sinha wrote.