HYDERABAD: City's car parks may help beat water scarcity during the impending summer of 2020. Experts in Hyderabad say that for the city, the only sustainable option ahead would be to utilise common urban spaces to harvest rainwater falling on the rooftops of buildings.
Interestingly, NGOs in Hyderabad are turning car parks of 10 by 20 feet or lesser into those with underground storage tanks that are 6-feet deep with up to a capacity of 32,000 litres. This can help a family of five last for over 100 days without Manjeera or Krishna water, assuming their consumption is 110 litres every day.
How does this work? Kalpana Ramesh, the head of the water initiative of SAHE NGO, explains: “Every year, Hyderabad sees about 80-90 days of rainfall wherein at least 85,000- 95,000 litres of water can be accumulated in only 1000 square feet or 100 square meters of a rooftop. This is enough to fill up three such tanks.”
This means that if all of the rainwater is collected, a family of five can have water for 300 days in three such tanks. To further explain the concept, the rain that West Zone of the city saw on June 22 that brought the IT corridor to a standstill, was of 8 cm and fell for roughly 60 to 90 minutes. If a couple of households or large apartment complex saved all of it on a 1 sq kilometre of area, they could have saved 5,000 tankers worth of water in just an hour! This would not just provide sufficient water for an entire community but would also help reduce water logging accompanying such heavy and short-lived showers.
Kalpana further explains that the basic design of such a tank would connect the rooftop of the house to a pipe, which would bring down all the water and first pass it through a filtration pit of 3x3x3 feet filled with sand and coal. Once passed through this, the water would flow into a tank of 10X20X6 or 8X8X6 or 6x8x6 size. This tank will then be linked to another rainwater harvest pit that is 6-feet deep or to an injection borewell to replenish the groundwater resource.
Kalpana says that this design can be replicated anywhere, once the existing space constraints are taken into account.“At the same time, it will be extremely useful for houses that have limited space. It can even be designed at the landing area under the staircase as well,” added Kalpana.
While the rainwater harvesting methods are more feasible for new houses, as the cost of construction itself can touch about Rs 80,000 to Rs 1 lakh, Kalpana explained that the over-head rooftop water can be linked to the existing water sump in the house as well after passing it through a filtration sump. The rainwater can also be directed to a sump around an existing borewell or injection borewell or directly into a dry, defunct borewell.
Rooftop area 1000 sq. ft of individual house
5300 sq. ft of a multi-storey building
Volume of pit
6000 l of individual house and 30,000 l of a multi-storey building
Total quantum available for recharge per annum
55,000 l for individual house
2,75,000 l for multi-storey building
Water available for 5-member family at 110 litres/day
100 days for 1 family
50 days for 10 families
Hyderabad receives about 80-90 K litres of rainfall every year on 1000 sq. feet area for 80-90 days.