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Recent media reports highlighting water contamination in Bangalore need scientific scrutiny and validity. Our research group has been analysing randomly collected tap water samples as well as borewell water in Bengaluru. Water quality analyses of tap water samples did not show chemical ions, nutrients or heavy metals, while some samples had pathogens, which may be due to age of distribution systems with the possibility of sewage mixing with drinking water due to leaky pipes, etc.
Contaminations like Ecoli can be removed through boiling. Hence, the best option for Bengalureans is to boil the tap water and use it rather than using commercial firm driven treatment systems at home.
Unnecessary sensation among innocent citizens will push them to adopt treatment systems at home, which would only help commercial firms to sell more reverse osmosis (RO) filters, whose long-term damage to the health of people and society at large goes unnoticed.
RO purifiers use membrane technology to filter dissolved impurities, the impure water is filtered out and is often called waste water or reject water. It however does not distinguish between the essential and non-essential (contaminating or harmful) minerals and removes all minerals. Moreover, for every litre of treated water, 4.5 liters of water is wasted and there are challenges for disposing the reject water from RO.
There are serious quality issues with the groundwater in the vicinity of lakes with the sustained inflow of untreated sewage and industrial effluents. Higher levels of nitrates and heavy metals in the ground water not only reflect the irresponsible behaviour of industries (of not treating effluents and discharging clandestinely in our water resources – lakes and borewells) but also prevailing poor and inefficient regulatory mechanism in the city. About 45% of Bangaloreans depend on groundwater and also groundwater table is declining due to poor recharge options with the paved landscape of Bangalore. Natural geological strata at higher depth has trace elements and the study reveals that groundwater at depths greater than 1000ft will be poor in quality.
Another major danger is from the ammoniacal nitrogen often found in sewage, waste water and leachate as it later gets converted into nitrate. Nitrates pose health hazards. Nitrate in drinking water can cause blood disorders and also stomach and intestine cancers.
The solution to water contamination is in demanding government agencies to do their work efficiently. Unplanned growth, unregulated development activities and fragmented governance with the lack of coordination between civic agencies are the issues that need to be fixed on priority to ensure quality services.
The 741 sq km landscape of the city has witnessed calamitous changes with the decline of green cover, water bodies. The city with green cover of 68% in 1970s was aptly branded as 'garden city'. The green cover has come down to less than 3% as the built-up area constitutes 81% of the landscape. This has made the region GHG rich, water scarce, non-resilient and unlivable, depriving the city dwellers of clean air, water and environment. This also highlights the need to decongest Bangalore, rejuvenate vital ecosystems – lakes and greenery in the city to ensure our children are healthy.
The very assumption that Bengaluru has water is wrong. Decision makers and educated elite are sitting in silver towers come up with unrealistic proposal of river diversions. Attempts to get water from ecologically fragile Western Ghats will only spell disaster in the fragile Western Ghats with frequent floods, droughts and landslides as is happening in recent times. We are stopping at no length to bring water from outside to Bengaluru.
We meed decentrailised, sustainable and economically viable mechanisms of rain water harvesting (through rejuvenated lakes) and treatment and reuse of waste water. Bengaluru receives annual rainfall 700-850 mm and harvesting of rain water gives us about 15 TMC which is about 70% of the city’s demand. Treatment of wastewater (about 18 TMC) through integrated treatment option of secondary treatment plant with the constructed wetlands and algal pond, will give us an additional 15-16 TMC. This means the city landscape has potential of 30-31 TMC, if we manage our water efficiently.
In fact, the scale of the problem becomes obvious if one takes a hard look at places like Varthur and Bellandur. People who can afford are wasting hundreds of litres of water every day while those earning a monthly salary of Rs 10,000 struggle to get a bucket of water. This also emphasises the need for water use efficiency with equity.
(The writer is professor and coordinator at Energy and Wetlands Research Group, IISc)
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