above-ground container, Amena Nadeem, bacterial contamination, Charcoal, chlorine, cleaning, collection, concrete, contamination, Costing, drain pipes, Filtration, GARDENING, groundwater, impurities, masonry work, materials and labour, mesh strainers, monsoons, plastering, PVC pipes, rainwater, Rainwater Harvesting, rainwater harvesting system, rock, rubble, sand, sanitation, sewer systems, soil, steel reinforcement, storage, Studio Subtractive, urban flooding, wain, water shortages, water treatment plants
With the monsoons upon us, it is pertinent to talk about rainwater harvesting – a technique that collects rainwater in homes and commercial buildings so the water can be used to serve a variety of purposes such as gardening, cleaning and sanitation, which, in turn, can help prevent water shortages that plague the country.
Rainwater harvesting consists of three stages:
- Collection. The first stage involves collecting rainwater from surfaces such as roofs and terraces. This water can be collected through drain pipes of the building. In order to ensure that the rainwater is free from dust and other impurities, the openings of the pipes are covered with mesh strainers.
- Filtration. The collected water is then filtered to clean it. The filtration mechanism involves making the collected water pass through materials such as charcoal, rubble and sand to remove impurities.
- Storage. The filtrated water is then stored in either an underground or above-ground container or tank and then utilised as needed. Water can usually be stored for four to five months without any risk of bacterial contamination, but chlorine is usually added in order to prevent contamination.
- Costing. The construction of a rainwater harvesting system includes the excavation of soil, rock, concrete as well as masonry work, steel reinforcement, plastering as well PVC pipes for channelling the water. The overall cost ranges between Rs 500,000 and 800,000 but may vary due to fluctuating rates of materials and labour, as well as the size of the plot on which the system is installed.
Ultimately, rainwater harvesting is an ideal solution for areas where groundwater supply is insufficient. Furthermore, rainwater harvesting prevents urban flooding (which can cause extensive damage and power shortages) and also reduces the load on already insufficient sewer systems and water treatment plants.
– Amena Nadeem
The writer is an architect at Studio Subtractive.
First published in the Real Estate Section of The DAWN National Weekend Advertiser on July 14, 2013.