It’s urgent, B’luru: harvest, recharge, recycle water

The summer is upon us and the discontent over water is giving sleepless nights to housewives and jitters to the city fathers. One does not know if the copious rains that visited us last year will keep a date with the reservoirs through which our lifeline, the river Cauvery, flows. With Bengaluru maintaining a rapid pace of expansion, only farsighted and cogent planning can ensure sufficient water for its citizens.

Currently, Bengaluru’s water needs are fulfilled from two sources, Cauvery river and groundwater. With a total of 29 tmc (1 tmc=78 million litres per day, or MLD) of Cauvery water, the gross availability for BBMP is 2,262 MLD. The statistics from BWSSB show that it does not get revenue for 41% of the water it supplies. Of the 27 lakh households in the city, only around seven lakh get metered BWSSB water. It is estimated that another four lakh households also receive BWSSB water through unauthorised connections, unmetered supply, and faulty meters. One study had uncovered 1.5 lakh unauthorised connections. Of these 80,000 are in 375 slums in the city. Plenty of water is also supplied through 15,000 public taps. Rest of the non-revenue yielding water leaks through old, rickety network of pipes. It is not altogether a waste as it recharges groundwater.

For the current population in the BBMP area, the net availability of water is 1,470 MLD. Of this, 300 MLD is claimed by the industrial-commercial establishments, leaving 1,170 MLD for domestic use. This makes the availability of water at just 100 litres per capita per day (LPCD). The BBMP population is projected to rise up to 19 million in 2030. Thus, Cauvery water availability will come down to only 62 LPCD by then. If the population goes up to 25 million (which is not an impossibility) by 2050, the per capita availability per day will further come down to 47 litres. By WHO standards, an individual deserves 135 litres of water a day.

Inter-state discord over sharing of Cauvery water does not leave any scope for the BWSSB to draw more from it. Moreover, the cost of pumping water from that far and its distribution in the city is computed at Rs 29 a kilolitre.

The second source — groundwater — is fast depleting and can be struck only at a depth of 800 to 1,000 feet. Money spent on sinking a majority of the borewells in the city during the last decades has gone waste as half of them have gone dry with the falling water table eluding their grasp. Going by the dying lakes and the unchecked exploitation of groundwater by construction companies, even the remaining borewells are anticipated to become defunct by 2020.

There are a few more disconcerting facts emerging from recent studies that need to be taken into consideration. The rainfall in the Cauvery catchment area has come down by 19.5% over the last two decades. A report by the Department of Mines and Geology had pointed out that 52% of the borewell water and 59% of tap water in the city is contaminated with sewage water and is not potable.

Privatisation of natural resources

Initiatives like the Lake Development Authority (LDA) are viewed with grave scepticism by environmentalists. They feel that parastatal organisations like LDA, more often than not, are created to mask the reality of privatisation of natural resources rather than to conserve them. Within our own lifetime, we have been witness to the number of lakes in the city coming down from 200 (in 1970) to 140 now – mostly on paper. And nearly all of them are gasping for breath.

Grieving on the loss of lakes or leaked water is not the solution. What could be the alternatives to cater to the city’s water needs? The scenario is not all that gloomy. Monsoon precipitation brings 92 cm of rainfall to Bengaluru in an average year with 57 rainy days. This amounts to 21 tmc-ft of rainwater. Of this, 3.6 tmc-ft falls over the roofs of 16 lakh properties which collectively cover 110 sq km or roughly 14% of the total area of the city. This water is well within reach of being tapped if property owners can be persuaded to put in place an effective rainwater harvesting system. This may look easier said than done.

According to A R Shivakumar, scientist at the Karnataka State Council for Science and Technology, the cost of tapping rainwater works out to be Rs 2.50 for every 1,000 litres once the initial pipe-sump infrastructure has been laid. Besides, the BBMP could channel the rainwater into the soak pits by imparting an appropriate gradient to terrain.

Even the rain falling on open spaces (17.6 tmc-ft) can be made to flow into the water bodies and preserved. Lakes serve to recharge the ground aquifers and sustain the water table in the ground, besides enhancing the aesthetics of the cityscape and tourism potential. They also support the ecosystem and bring climatic benefits by providing cooling surface for air.

Large establishments such as the Railways, Defence, education and research institutes and industries should be asked to recycle used water over and over again. In this context, a legislation permitting groundwater withdrawal commensurate to water recharge on the property needs to be thought of for large establishments.

Under the UN Sustainable Development Goals (SDG), member-nations are called upon to ensure universal and equitable access to affordable water and sanitation. This entails reducing pollution, minimising release of hazardous chemicals and materials into water, halving the proportion of untreated wastewater, and increasing recycling and safe reuse of water. Besides rainwater harvesting, action would thus be needed to boost wastewater recycling.
(The writer is a member of the Bangalore Environment Trust)