Simple yet effective

CPCPC india is a construction company based in Nagpur with an office at Gurgaon. It is involved in prestressed concrete construction. The company is propagating the use of prestressed concrete tanks for capturing rainwater.

The process of prefabricated construction is a mechanised one. Repetitive elements are cast through moulds. This is a characteristic of a precast operation. These moulds are generally made of steel or wood and can be machined for low tolerance. High quality can therefore b ensured.

Prefabricated tanks for water storage offer several advantages:

a) The life span of the tank is about 100 years as compared to ferrocement tanks which have a life of between 10-15 years
b) The tanks are maintenance free can be cleaned easily
c) These tanks do not require heavy equipment for their installation and can be dismantled and reinstalled
d) These tanks can be used on rooftops as well as underground.
e) Cost of construction is low – about Rs 1.50 per litre of storage capacity

Precast water tanks below footpath to capture rainwater

These prestressed tanks can be used to store rainwater or recycled water. These tanks can also be used to store water harvested from pavements and footpaths. In urban areas, space is the constraint and these tanks can be placed below the pavements, before the pavements are constructed, or, during their repair. If provisions are made during the planning stage, the cost can be covered by filling material cost and the top finish of the tank can be matched with the interlocking pavers design (see Figure 1).

Effective use of precast tanks below compound walls

These tanks can also be placed below compound walls (see Figure 2). Water from the entire compound area is collected in these tanks which otherwise would have gone waste.

Another suggestion offered by CPCPC india is the construction of bore pits using augurs. Bore pits of one metre depth can be dug using augurs on barren lands, roadsides, near playfields, forests, pathways and on bunds adjacent to fields before the monsoon. The purpose of these pits is to store water for longer periods of time so

Augurs to assist in recharging groundwater

that percolation time increases and the water penetrates into the soil rather than just flowing away.

These augurs can be attached to tractors (see figure 3).

The pretressed concrete technology is considered to be economical, long lasting, strong and durable. It has proven to be versatile technology for rainwater harvesting.