It is rare to find a kitchen without an RO these days. Several societies even run supply water through an in-house RO before distributing it as drinking water to residents.
ROs are used to reduce the Total Dissolved Solids (TDS) value of contaminated water to render it safe for drinking. However, experts say that consuming water with low TDS value can actually be harmful to health.
Dr Charu Goel, senior consultant in the Department of Medicine, Venkateshwar Hospital, Sector 18, Dwarka, says,"Purifying water to a very low TDS value strips it of its mineral content. Some minerals, such as calcium and magnesium, are essential for the proper functioning of the heart and the nervous system. Low magnesium levels are associated with higher cardiovascular mortality. Consuming water low in minerals can also disturb homeostasis, leading to loss of sodium and potassium from the body, which, in turn, can impair kidney function. Water low in calcium is associated with brittle bones, tiredness and muscle cramps. Ingesting water low in minerals can be especially harmful in humid countries such as India, where people lose a lot of minerals through perspiration."
Dr RK Pandey, Director of Orthopaedics, Rockland Hospital, Dwarka, and a resident of Manchahat Apartments, Sector 10, is also of the same opinion. He says, "Water deficient in calcium and magnesium leads to brittle bones and adversely affects the neurological system. Bones become prone to fractures, and muscle fatigue, irritability, loss of memory and difficulty in concentration become common."
People either use packaged water or water purified by ROs set to their highest efficiency. The TDS value of water from both sources can be as low as 30. Ironically, most of us feel safe consuming it.
"The water supplied by Delhi Jal Board [DJB] should not be purified further," says Dr Anil K Mishra, assistant bacteriologist, quality control, DJB. "It is already fit for consumption and has zero contamination. Consuming water with low TDS can cause severe metabolic disorders over a period of time. It is important to make sure that the RO-purified water does not have a TDS value lower than 100 mg/l, as this water tends to absorb toxic chemicals from the containers they are stored in. In addition to being less palatable, this water, when used to cook, leaches out important vitamins and minerals essential to the human body."
Arvind Rudra, a resident of Harmony Apartments, Sector 4, and Environment Quality Management Consultant, Green Growth Trainer (UNESCAP, AIT Thailand), says, "We are wasting water by using ROs to purify already-potable water. In most cases, the water purified by an RO has a TDS lower than 100 mg/l, the limit set by WHO for palatability of water. We need to be intelligent about this and discourage people from wasting water this way."
Forensic expert, Deen Dayal Upadhyay Hospital, Dr BN Mishra, says, “The pH of the human body is 7.4 and water plays a significant role in maintaining this. Water with a low TDS value tends to be acidic, as its pH value is less than 7. Overpurified water may cause a pH imabalance in the body, leading to several metabolic complexities."