bangalore rainwater harvesting is a winwin situation for all borewells are full the quality of water is better and the city gains declares david saldanha a resident of residency road faced with dipping water level in the two borewells in the area in 2010 saldanha did not throw up his hands instead he opted for rainwater harvesting to recharge the borewells estimating the annual rainfall in bangalore at 1000 mm he says he is able to harvest 1 million litres of rainwater annually and also breathe life back into the borewells the water level in the two borewells ran lower than 100 metres deep and the yield was low the advantage is continuous water supply and les power consumption to pump up water im thrilled with the result the water yield has gone up and its quality is much better too says saldanha saldanhas success story deserves to be emulated across the city especially with the monsoon around the corner experts say onethird of the citys water demand can be met through rwh experts term rainwater harvesting one of the best ways of conservation more so at a time when bangalore faces acute water scarcity harvesting in urban areas is the process of collecting filtering and using rainwater which falls on roofs and on porticos and is channeled in three ways recharging borewells replenishing groundwater and collecting rainwater for reuse later creating awareness and making people understand its importance is critical for the successful implementation of rwh in bangalore people should be ready with rwh structures in their premises before the arrival of the monsoon they can store the rooftop runoff in underground sumpstanks for washing or gardening or let it run into the earth to recharge the groundwater table said vivekanand honnungar associate fellow from the water resources division at the energy and resources institute teri southern regional centre bangalore rwh was made mandatory for individuals taking up construction on sites measuring 30ftx40ft or more and in structures standing on plots of 60ftx40ft or more but bwssb has been unsuccessful in implementing the rule in advanced countries rwh is often used to supplement the main water supply its used to conserve water in drought conditions mitigate floods in lowlying areas and even reduce the demand on wells which in turn reduces stress on the groundwater table rainwater is also potable as its the purest form of water free from salt and other minerals dissolved ions are present in rainwater in the range of 13 mg litre so its considered very pure and can be used for regular purposes moreover the ph is between 67 and 72 which makes it fit even for consumption but the quality varies from one area to the other said michael sebastian baptist the founder of farm and rainwater harvesting systems baptist runs a vehicle all over the country to educate people on rainwater harvesting methods and gives live demonstrations toodirect recharge direct borewell recharging is about collecting filtering and storing rainwater in subsoil