How much will it cost to catch rain?
When community come together to harvest rain, the per-capita investment goes down. For instance, Panchsheel Park Colony about 1000 residents pooled in
Rs 4.5 lakh to harvest more than 170 million litres of water annually.
Rainwater harvesting methods are site specific and hence it is difficult to give a generalised cost. But first of all, the major components of a rainwater harvesting system - rain and catchment area - are available free of cost. A good proportion of the expenses would be for the pipe connections. By judiciously fixing up the slopes of roofs and location of rainwater outlets, this could be brought down considerably. However the cost varies widely depending on the availability of existing structures like wells and tanks which can be modified and used for water harvesting.
Typically, installing a water harvesting system in a building would cost between Rs 2,000 to 30,000 for buildings of about 300 sq. m. The cost estimate mentioned above is for an existing building. For instance, water harvesting system in the CSE building in Tughlakabad Institutional Area, Delhi, was set up with an investment of Rs 30,000 whereas those in the model projects ranged between Rs 70, 000 and Rs 8 lakh. The costs would be comparatively less if the system were incorporated during the construction of the building itself.
Some basic rates of construction activities and materials have been given here, which may be helpful in calculating the total cost of a structure. The list is not comprehensive and contains only important activities meant to provide a rough estimate of the cost.
a. Unit cost of construction activities.
Item
|
Unit
|
Rate (Rs.)
|
| Excavation in soils | cu. m. | 90.00 |
| Excavation in rock | cu. m. | 150.00 |
| Brickwork with cement mortar (1:6) | cu. m. | 1400.00 |
| Plain cement concrete (1:3:6) | cu. m. | 1500.00 |
| Reinforced cement concrete (1:2:4) cu. m. 4700.00Including steel bars, shuttering etc. | cu. m. | 4700.00 |
| PVC piping for rainwater pipes - 110 mm diameter - 200 mm diameter | Metre metre | 165.00 275.00 |
| Making borehole in metre 165.00Soft soil (with 150 mm diameter PVC casing) | metre | 180.00 |
b. Ferrocement tanks with skeletal cage
Capacity of rooftop water harvesting system in litres
| |||||
5,000
|
6,000
| 7,000 | 9,000 | 10,000 | |
| Total cost in rupees | 12,430 | 12,975 | 13,970 | 14,380 | 15,800 |
Source: Action for food Production and United Nations Children's Fund, Rooftop rainwater harvesting systems
c. Plastic tanks: Available as finished products in various capacities. The cost of these tanks ranges from Rs 2/litre to about Rs 3.5/litre.
Other brands available in the market
Brand name
|
Unit cost (Rs. Per litre)
|
| Hindustan, Jindal | 1.80 |
| Storex, Ganga | 2.75 |
