A study taken by the Centre for Symbiosis of Technology, Environment, and Management (STEP) approximated that 40% of the population of Bangalore is dependent on groundwater. There are around 125,000 private bore wells in the city. Because the extraction of groundwater is highly unregulated, the water tables have been rapidly depleting. According to R. Vasudevan, a chief engineer of the Bangalore Water Supply and Sewerage Board (BWSSB), the water levels have dropped 300 feet below ground level. The BWSSB extracts the majority of the water they distribute from the Cauvery River. This river is located almost 100 km away from the city and at an altitude of about 1,500 feet below that of the city. Because of this, approximately 75% of the total BWSSB revenue is spent on electricity charges. Another huge problem exists – almost 30% of the water extracted is lost to corroded and broken piping systems.  The piping system in the city is over 50 years old. Many of the pipes are in horrible condition, producing many leaks. Unfortunately, the BWSSB has only made temporary fixes to repair the decaying pipes rather than to replace them entirely.

With such water shortages looming over the city, it is essential for changes in the water policy of the city to take effect. The BWSSB has just mandated rainwater harvesting last year as an amendment to the Bangalore Water Supply and Sewerage Act of 1964. The amendment states that all buildings with a total rooftop area of 2400 square feet or greater must install a rainwater harvesting system; all proposals for buildings with a total rooftop area of 1200 square feet or greater must include plans for a rainwater harvesting system. In order to see how effective rainwater harvesting can be, I have prepared a basic water balance of the city. The following values necessary for a balance were found. Some of the metrics were determined by simple calculations.

Rainfall Data:
Area of the City	709,500,000 m2
Amount of Average Rainfall	0.859 m
TOTAL Amount of Rainfall in the City, Annual	609,460,000 m3
Water Demand Data:
Per Capita Water Demand*	150 L/person/day
Population of the City	5,840,155 persons
Water Demand for Domestic Use, Annually	319,748,486.3 m3
Daily Water Demand for Other Uses**	587,000,000 L/day
Water Demand for Other Uses, Annually	214,255,000 m3
TOTAL Water Demand, Annually	534,003,486.3 m3

*Please Note: This value is standard set by the Central Public Health and Environmental Organization. However, this is an overestimate of the per capita water use daily. Studies show that many people use only around 100 L of water per day.

**Please Note: This value encompasses the demand for commercial establishments, industrial users, institutional users, grounds (municipal and industry), fountains, and unaccounted for water (leakages). This data was gathered from surveys and interviews. The values were obtained from the Resource Optimization Initiative:

Eckelman, M. J., Shenoy. M., Ramaswamy, R., Chertow, M. 2010. Applying industrial ecology tools to increase understanding of demand-side water management in Bangalore, India. (unpublished manuscript).

If we look at the total amount of rainfall on the city and the total water demand, we see that the total rainfall is only slightly greater than the total water demand. We must take several things into account. First of all, it is not possible to capture 100% of the total rainfall. If we approximate that 70% of the total rainfall can be effectively captured to recharge aquifers, lakes, and bore wells, then the total water demand exceeds the amount of rainfall captured. This shows the severity of the water shortages in Bangalore. The numbers are too close to each other for comfort!

In order to alleviate the water scarcity issues, a greater campaign to install rainwater harvesting units should be invested in. People should be made aware of the advantages that rainwater harvesting can have. In addition, the BWSSB should work to expand their water reuse programs. Currently less than 1% of water is recycled for reuse. More sewage treatment plants should be installed to increase this percentage. There are many ways to solve this water crisis. Small steps can yield large results. Installing a rainwater harvesting system can be as cheap as 400 Indian Rupees (Approximately $8.50). The installation of such units will help both the people and the environment. The citizens of Bangalore can reap the benefits of sustainable water management while the environment can enjoy its water sources being replenished.

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