COMPONENTS OF RWH SYSTEM

Any Rain water harvesting system has three components

  • Catchment
  • Conveyance
  • Storage

Catchment

 Any surface can act as the catchment for rainwater harvesting. Rooftops are favoured because of the large coefficient of run-off generated from them and the relatively less likelihood of their contamination. Paved areas, footpaths and roads are also good rainwater runoff generators and with adequate catchment management strategies can provide good quantity and adequate quality of runoff water for use. Unpaved areas also generate runoff during heavy storms and can be modified to act as rainwater catchment.

Conveyance

Conveyance systems can be the catchment surface itself acting as a sheet runoff. For rooftops rainwater gutters and rainwater down pipes are conveyance systems, which need to be designed appropriately so as to manage the severest intensity of rain as well as not to lose any water during the conveyance process. Storm water drains, French drains with pebbles are also conveyance systems.

Storage

 From the simplest ground level tank, to underground sumps, surface lined ponds and large lakes storage options are many depending on the context of the rainwater harvesting design. In many a case the soil profile may also permit artificial recharge of rainwater to open wells and borewells where water can be stored to be retrieved later for productive use. 

why harvest rainwater?

  • Water availability per capita has been on the decline in India. Two reasons have been the increasing demand for water and the increasing population. The quantum of water available to the country being fixed the increasing demand reduces per capita water availability. 
  • Agriculture continues to be the single largest consumer of water however industrial demand for water shows the fastest growth.
  •  It makes ecological and financial sense not to waste a pure natural resource available in large quantity on one’s roof.
  • In the case of a homebuilder, at an initial stage of construction, investments in time, design and money are minimal for adopting roof rainwater harvesting.
  • Ground water sources are increasingly getting depleted or are getting polluted. Bore wells are either silting up, getting short of water or are drawing polluted water.
  • Private purchase of water from tankers is unreliable in quality and is also expensive.
  • It encourages water conservation and self-dependence.
  • It is being recognized that people from various sectors have to become partners in the solution process and not remain simply as institutional beneficiaries.
  • India is blessed with adequate rainfall as a whole, yet there are large swathes of dry, drought prone area. In many other places the quality of groundwater is not good. In such places rainwater harvesting can provide lifeline water for survival and more.

What is Rainwater Harvesting?

Rainwater Harvesting means the accumulation and storage of rainwater where it falls and using the same. It is way of saving the rain water which otherwise flow off to drains. It can been used for non-drinking purpose, water for livestock, water for irrigation or to recharge groundwater.

 

Why should I harvest rainwater?

Water is becoming a scare commodity, with every passing day. Water tables have fallen significantly in most areas and there is a significant pollution of groundwater from natural as well as man-made sources. Future wars are likely to be fought on the issue of water.
Rain water is freely available, and can reduce the dependability on water supply from other sources. It can also be useful to save on water bills and responsible use of a precious resource to make a difference to our environment.

 

How much water can it save?

It can save up to 30% to 50% of treated drinking water, depending on your normal usage, in the household. It can save up to 80% in large commercial building.

 

Is rain water harvesting propagated in recent times?

No. Our ancestors harvested rain just as naturally as they use the ground to grow crops. We lost touch with these local solutions. But once again, we will have to rely on these methods, as water is becoming scare.