The annual rainfall in Chennai is in the range of 1200 - 1300 mm
On an average Chennai receives rainfall for 300 hours throughout the year
The city receives more rainfall during north-east monsoon i.e., in the month of October to December
After the severe drought of 1992 & 1993 Metro Water began to take active part in promoting rain water harvesting
The main sources of public water supply in the city are the three reservoirs - Poondi, Redhills and Cholavaram - with an aggregate storage capacity of 175 MCM.
Cost of metro water tanker 10kiloliters varies from 600-850 rupees depending on the type of occupation
At the peak of summer 2002 year, a 12,000 litre tanker of water cost as much as Rs 1,500 to Rs 2,000
there is a total of about 800 Kms length network of storm water drains in the city
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)
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
Water Management System BORE WELL /GREY WATER PIT OVER HEAD TANK
Sources of Grey Water SIDE STRAPPED TANK CAN BE RECYCLED AND USED
Grey water Systems
Grey water refers to the reuse of water drained from baths, showers, washing machines, and sinks (household wastewater excluding toilet wastes) for irrigation and other water conservation applications.
Existing Rain water Pit
The site consists of two floors with four dwelling units. The total number of people dwelling is 20.
The existing pit is of 2 feet X 2 feet X 30 dimension. This has the capacity of 3398 liters of water .
Total roof top area 60sqm
Total consumption per day 2700
total grey water produced 1300liters per day
800 liters of grey can be reused to flush toilets
SOURCES OF WATER
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
Design Solutions & Benefits
Water friendly building design
DESIGNING BUILDINGS FOR WATER
Designing with buildings which are self contained with water storing methods rather than filling up the house with water drums.
The method used consists of two horizontal ferro cement pre cast units of size 4m X 1m
These units are present in each of the floors
These units can be supported by the lintel beams of the existing building or they can be supported by the floor slab the other options are floating columns.
Other materials like PVC pipes with large diameters can also be used as storage units
For good aesthetical appearance fiber glass can be used
Making rain water 100% efficient by using rain water directly by connecting tank to water closet and tapping it without even flushing the first rain
Rain water which is not used for consumption directly can be used for non portable
1.5m 1m Area of the tank 1sqm Height 1m Volume 1000L OF WATER
Maximizing the water usage during rain
Save electricity used to pump the water to the over head tank during rains by directly using water from these tanks
During summer time this tank can be used to store geen water which is treated at the roof level
Great aesthetical appearance since they can b designed as per the building styles
Landscaping can be done over these to further improve the design
Over head water tank over flow water can also be saved
Do not occupy space or cause any hindrances like the water cans or drums since they are designed at the initial stages of planning depending on the water requirement
The tank is left unused in case there is no rainfall
There will be 2 or 3 different plumbing lines
if in case the tanks are used to store grey water during summer they must be cleaned and maintained well before the rain starts
Water proofing must be done carefully else chances
Of water seepage into the walls
Design Solutions & Benefits For future projects Sunken slab for grey water treatment landscape . Size of tank to store 1000L of water 1mx2mx