Rainwater harvesting is accumulating and storing rainwater for reuse without allowing it to run off. For thousands of years, humans have survived in the desert by skillfully managing the scarce resource.
The water we obtain from the rain is collected in a tank or well for later use. Because there is water flow only for a brief period, storage is important in rainwater harvesting.
Rainwater harvesting can help mitigate flooding in low lying areas. The harvested rainwater also helps recharge ground water by reducing the demand on well water. Similarly, in highly populated urban areas, this technique can provide easy access to water and reduce the cost of fetching drinking water.
In an arid area, every drop of water falling as rain counts, and its conservation for the future is the soul of this technology. In an urban setting, the roofs of our homes form the best catchment areas.
The Kathmandu Valley is said to receive about 1600 millimeters of rain a year, and on a typical rooftop, more than 160,000 litres of rain are available for capture. Thus, utilising this rainwater would meet about half the demand of Kathmandu.
Based on different studies, rainwater is taken as a clean source of water, often better than groundwater or water from the rivers and lakes. Water
harvested from the rains can also contain pollutants, such as dust, lichen, fungal spores and bacteria, pesticides and various dissolved harmful gases. So, rainwater can be harvested safely by diverting the initial flow of water into the drainage.
Similarly, pre-filtration technique is best employed in big operations to ensure that water collecting in the tank is absolutely free of large pollutants.
Harvesting rain is a practice that has been around for centuries. It has been widely used in different developed nations and also the underdeveloped countries that have no feasible water resources and depends solely on rain for day to day life.
Rainwater harvesting technique is the best method to cope with the problem of water scarcity in densely populated cities as well as in droughtprone areas of Nepal. Water is getting depleted in the mountain region of Nepal also due to
the declining glaciers, which are beyond Nepal’s control.
Creating reservoirs of water from rain during the surplus period is a wise step to be taken. Exploring and collecting drops of water from the rain will help make life easy on the planet.