- 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 175 million cubic meters. - Greywater refers to wastewater from baths, showers, washing machines and sinks, excluding toilet waste, and can be reused for irrigation and other purposes. Existing rainwater collection pits in buildings are typically small at 2x2x30 feet. - The design proposes installing larger precast ferrocement or PVC water storage tanks of size 4x1 meters in buildings to better collect and store rainwater and greywater, reducing reliance on municipal water supplies.

3. Jan...1.2 Feb...0.3 Mar...0.2 Apr...0.6 May...1.5 Jun...2.4 Jul...3.9 Aug...5.4 Sep...4.8 Oct...11.1 Nov...14.0 Dec...5.6 Average Monthly Rainfall in Chennai (in inches)

4. Water Requirements per person Purpose Litres Per day Litres Per month Litres Per year Drinking 3 90 1080 Cooking 4 120 1440 Flushing 40 1200 14400 Bathing 20 600 7200 Washing clothes 25 750 9000 Washing Utensils 20 600 7200 Gardening 23 690 8280 Total 135 4050 48600 Grey water 65 1950 23400

9. Building Layout Water harvested in the building with a flat terrace area of 60 sq .m The average annual rainfall in Chennai is approximately 1300mm. In simple terms, this means that if all the rain that falls on the terrace is retained, then in one year there will be rain water on the terrace floor to a height of 1300mm. Amount of water required per day ---20X135 = 2700L Water reused [GREY WATER ---20X63 =1260 Hence the water harvested is insufficient and needs more of water management systems Area x Height of Rainfall 60 sq. m. x 1.30 m :78 cu. m. (78,000 liters) Volume of rainfall over the Terrace Assuming that 90% of the total rainfall is effectively harvested. Volume of water harvested = 78000x0.9 = 70200 liters That means ( 70200 / 365 ~ ) 192 liters of water per day will be available for the household. Water required per day 72L/PERSON portable water :1.30m (1300 mm) Height of rainfall :60 sq. m. Area of Terrace

11. 1.5m 1m Area of the tank 1sqm Height 1m Volume 1000L OF WATER

14. Design Solutions & Benefits For future projects Sunken slab for grey water treatment landscape . Size of tank to store 1000L of water 1mx2mx

15. References www.akash-ganga-rwh.com http://www.chennaimetrowater.tn.nic.in/rwh/rainwaterwhy.htm www.rainwaterclub.org http:/www.livingroofs.org/livingpages/