Water is critical for human existence and ensuring an accessible, potable, and safe water supply for the population of1.38 billion is a big challenge but a basic necessity as well. Water scarcity and demand, have been escalating with an increase in the population for both, personal as well as industrial use, and all of us are aware that this growth is exponential.
When we glance at the globe which is 70%covered with water, it’s difficult to buy the fact that hardly 2% of this is fit for consumption and hence the shortage. Lately, we have been experiencing droughts at various parts of the world as a result of irresponsible falling levels of groundwater table due to the spread of hard-impervious surfaces. Hence the question arises, what can we do differently?
Don’t worry we’ve got you covered, the answer is Rainwater harvesting- to tackle the challenges of tomorrow while facilitating the ease of today. This system is lately in light because of the alarming situation but its roots lie deep into the traditionally prevalent baoli’s (stepped wells) and structures of Gujarat and Rajasthan for meeting the water requirements in their deserted lands. Zai and half-moon rain water harvesting techniques for soil and water conservation canal so be identified in the Sahel, West Africa.
What is Rain-water harvesting anyway? It’s a way of water conservation by storage and recharge, which is otherwise lost through surface run-off or evapotranspiration. Rainwater is free from organic matter and bacteria apart from being soft in nature which makes it an important resource. If this water is not taken care of, it might end up in stormwater drains adding up extra contaminants to it, which ultimately will be of no use. It also helps in reducing the unsanitary drainage congestion during heavy rains in urban areas.
The planning of rainwater harvesting systems should be done well in advance during the conceptualization and site planning process so that it can be integrated with the landscape and building plans to reap maximum benefits. There are essentially two ways to harvest rainwater, which is through:
The pattern of the water that incidents on-site is deliberately modified to artificially increase the recharge of groundwater. The basic mechanism is to collect rainwater in a pit or a trench which is typically layered up with various sizes of pebbles and aggregate forming a natural filter, freeing the water of pollutants like organic matter. The water is allowed to stay there and slowly dissipate through the trench until the water percolates into the aquifers. Some systems like Recharging Bore Wells/ Pits/Shafts, Soakaways, or Percolation Tanks can be set up in the building premise by providing proper slopes to channelize the water into them efficiently.
Another strategy could be reducing the imperviousness of our urban areas and carefully using pervious material that let water percolate and reduce run-off, planting indigenous species also improves seepage because of their native adaptability. However, it should be kept in mind that such rainwater harvesting systems are not recommended for places with a high water table.
Water falling on the rooftop of our modern homes can be easily harvested and a provision for the same should be a must in every new infrastructure. Rooftop rainwater harvesting requires minimal equipment majorly operating with low-maintenance strategies. The rain falling on the roof is collected on its surface which is called the catchment area and is further transported by the means of drain pipes, gutters (for a sloping roof),and downpipes. Since the water is collected off the roof, it is not sterile anymore and needs to be treated in the filter unit to avoid degradation of biological material and development of odor. Numerous innovative devices are available in the market of considerably compact sizes which filter the water and further send it to the storage tank, some of the basic types include –Charcoal Filter, PVC Pipe filter and Carbon Filter, these are needed to be cleaned quarterly. The stored water can be used for gardening, flushing, washing, etc. but has to be further filtered to be fit for potable use. This assembly can also be supported with pumps and pressure tanks for obtaining the required flow of water, empowering its usage.
Harvesting water has numerous benefits for the user and the environment as well. Using rainwater for recharging your borewells or the groundwater, one can benefit from it in difficult times of water shortage. It can considerably reduce one’s water bills with a small initial investment. Large housing campuses can strive to achieve full autonomy for their water demands and not rely on municipal mains by integrating the use of rainwater with water-efficient systems (drip irrigation, water closets, urinals, flush tanks etc.) Besides, all green building rating systems dedicate substantial points for water efficiency, which makes it mandatory for all green practitioners to indulge in this practice.