- Chennai receives an average annual rainfall of 1200-1300mm mostly during the northeast monsoon from October to December. The three main reservoirs that supply water to the city have a total storage capacity of 175MCM. - Water requirements for a person range from 90L per day for drinking to 1200L per month for flushing, with the total daily requirement being 135L. Greywater production is around 65L per person daily. - Existing rainwater harvesting systems and potential for increasing reuse of greywater are analyzed to supplement drinking water needs, with designed ferrocement tanks proposed to better collect and store rain and greywater onsite.