The 4 taps approach- to sustainable urban water management

May 16, 2010


The ‘four taps’ approach


Bangalore can learn from Singapore, which obtains water from four different sources

Needed: More of such water recycling plants

As the city experiences water scarcity in some parts and launches a drive to drill new borewells to temporarily overcome the shortage it would be wise to remember the “4 taps approach” of Singapore. It famously developed and implemented rainwater catchment and storage in reservoirs, got water from Malaysia, recycled waste-water and desalinated water as its multiple sources of water.

Bangalore too can develop water from the Cauvery/Arkavathy, groundwater, rainwater and recycled waste-water as its “four taps.” This is already happening; however, a systematic approach will provide stewardship for all ‘four’ taps.

The solution is also scale independent, hence it can be included as a strategy by individual buildings, apartments, layouts, institutional buildings et al.

Consider the College of Engineering on Mysore Road. With a large campus and huge buildings, it requires both piped water and ground water. It invested in a rainwater tank and recharge structure to capture all the rain from the massive rooftops and built a huge sump to store it. In April itself , thanks to the showers, the tank filled up three times and provided the much needed supplementary water. Excess water from the sump will recharge the groundwater aquifers and keep the borewells charged.

Good impact

The institution will now actively consider waste- water recycling as the fourth source of non-potable water use. The single largest benefit is the demonstration effect for the students on stewardship of the environment.

Consider also this layout on Sarjapur Road to the east of the city which, when faced with water scarcity, invested in rainwater harvesting and groundwater recharge. The waste-water treatment plant has been made more efficient in operation and the treated waste-water is used for all landscape requirements. It now has borewells, rainwater and treated waste-water and waits for the Cauvery line to top up requirements.

With the mandatory rule for rainwater harvesting, every building in Bangalore now has a chance to augment its Cauvery supply or borewell-based supply with rainwater. It is a matter of time when greywater reuse too will come in, given the overall shortage of water.

With an overall shortage of water, wisdom lies in reducing demand to the optimum, not wasting water, and adopting the “four taps” approach. That is the way towards sustainability and water wisdom.




  1. on the consumption side, curious to know if the tippy tap is gaining ground with any design improvements.

  2. design improvements have come from the students of Shrishti…but for sure it needs more dissemination and implementation…maybe in the CIVIC projects?

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