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Purify water but keep nutrients

Water is also the source of sodium, responsible for maintaining extracellular electrolytic balance.

Saloni Goel | New Delhi |

How many of us know that crucial nutrients for physical development and well-being are obtained from the cheapest and simplest of sources – the water we drink. Calcium and magnesium, important for bone and cardiovascular health, are derived from drinking water.

Water is also the source of sodium, responsible for maintaining extracellular electrolytic balance. Copper and selenium are micronutrients for which our bodies depend on water. The drinking water standards (IS 10500: 2012), developed by the apex organization Bureau of Indian Standards (BIS), specifies the permissible limit for constituents in drinking water. For almost all constituents, it is the upper limit.

In a layman’s terms, water is considered fit for drinking if a given constituent is less than its specified permissible limit. Water is considered unfit for drinking if the limit is breached on the higher side. This approach to setting drinking water quality standards inadvertently paints all constituents with the same brush – as pollutants, undesirables or toxic. Consequently, water treatment is also all about reducing concentration of constituents to bring them within desirable limits, or basically filtering them out.

While this approach addresses the need to maintain purity of drinking water, it overlooks the need to maintain its nutritional value. It looks at the issue only from one side. It’s like wearing spectacles which offer correction in one eye, where it is required in both. The resultant view is bound to remain partially blurred, and not good enough. In order to address the whole problem, we need to address the other eye too. We need to define the minimum permissible limit for some select constituents of drinking water, which impart its nutritional value. A case in point is fluoride.

Water is a source of fluoride. Beyond a limit, fluoride is linked to dental and bone damage. However, until a certain limit the body needs fluoride to prevent dental decay. Similarly, it is advised that the TDS content of water should not exceed 500 milligram in one litre. But increasingly it is coming to attention that a drastic reduction in TDS is not beneficial for health either, as it deprives the body from some essential nutrients, notably calcium and magnesium. Hence, the thrust of water treatment, so far limited to reducing concentration of individual chemicals to acceptable limits, needs to be widened to include a minimum value for select chemicals, in order to incorporate the beneficial impact of water constituents.

This necessitates framing guidelines for setting minimum limits in addition to maximum. Separate guidelines are needed for piped water supply, bottled water, and isolated domestic treatment units. It seems entirely unnecessary that we first spend resources to remove nutrients from water, and spend money again to get them from artificial sources like pills and food additives. Surely we are smarter than that!

(The writer is an Environment, Sustainability & Sanitation Expert. She contributes as member in Expert Committees of Environment Ministry and CPCB and is an alumnus of IIT Delhi and London School of Economics)