A rainwater harvesting system comprises components of various stages transporting rainwater through pipes or drains, filtration, and storage in tanks for reuse or recharge.
The common components of a rainwater harvesting system involved in these stages are explained below.
1. Catchments:
The catchment of a water harvesting system is the surface which directly receives the rainfall and provides water to the system. It can be a paved area like a terrace or courtyard of a building, or an unpaved area like a lawn or open ground. A roof made of concrete, galvanised iron or corrugated sheets can also be used for water harvesting.
Image Source : water.wa.gov.au
2. Coarse Mesh:
ADVERTISEMENTS:
The coarse mesh is put on the roof to prevent the passage of debris.
3. Gutters:
Gutters are channels built all around the edge of a sloping roof to collect and transport rainwater to the storage tank. Gutters can be semi-circular or rectangular. Gutters need to be supported so they do not sag or fall off when loaded with water.
4. Conduits:
Conduits are pipelines or drains that carry rainwater from the catchment or rooftop area.
5. Filter:
ADVERTISEMENTS:
The filter is used to remove suspended pollutants from rainwater collected over roof. A filter unit is chambers filled with filtering media such as fibre, coarse sand and gravel layers to remove debris and dirt from water before it enters the storage tank or recharge structure. Charcoal can be added for additional filtration.
6. Storage Facility:
There are various options available for the construction of these tanks with respect to the shape, size and the material of construction.
7. Recharge Structures:
Rainwater may be charged into the groundwater aquifers through any suitable structures like dugwells, borewells, recharge trenches and recharge pits.
Various recharge structures are possible—some which promote the percolation of water through soil strata at shallower depth (e.g., recharge trenches, permeable pavements) whereas others conduct water to greater depths from where it joins the groundwater (e.g., recharge wells).
ADVERTISEMENTS:
At many locations, existing structures like wells, pits and tanks can be modified as recharge structures, eliminating the need to construct any structures afresh. One of the most commonly used recharging methods is the percolation pit, which is also called a soakaway.
Percolation pits, one of the easiest and most effective means of harvesting rainwater, are generally not more than 60 x 60 x 60 cm pits, (designed on the basis of expected run-off as described for settlement tanks), filled with pebbles or brick jelly and river sand, covered with perforated concrete slabs wherever necessary.