Rainwater Harvesting: A Viable Means To Prevent Water Crisis
By Saumya Jain
“Water, water, every where, / Nor any drop to drink”
These all too familiar lines from the poem by Samuel Taylor Coleridge seem to be ringing too close to home as water becomes an increasingly scarce resource with every passing day.
Water Crisis was ranked as the #5 Global Risk in terms of impact on society by the World Economic Forum in January 2020, making it an alarming issue requiring an earnest redressal. What is interesting is that it is not really about scarcity, but rather proper water management. To quote the World Water Council, “There is a water crisis today. But the crisis is not about having too little water to satisfy our needs. The crisis is managing water so badly that billions of people — and the environment — suffer badly.”1
For sustainability, a healthy relationship between natural cycles and the available natural resources is a must. To further this objective and protect the existing reservoirs, rivers, aquifers, and ecosystems from further destruction, one needs to harness the largest and most accessible resource currently going down the drain: Rain.
What is noteworthy is that harnessing rain neither requires no energy nor any natural resource; on the contrary, it helps preserve the much-needed fast depleting resource: Water.
Rainwater harvesting is an ancient concept that is simple to implement and scalable. Simply put, it is the act of collecting rainwater and storing it for later use.
Rainwater harvesting systems have many an avatar, from the basic rain barrels to collect rainwater to more intricate structures with pumps, tanks, and purification systems.
Rainwater collected through any system is fit for reuse. Without filtration and purification, it finds use in most functions minus consumption — e.g., flushing toilets, washing cars, irrigation etc. Once put through the purification process, it is fit for consumption as well.
In urban areas, the rain falls on roofs, buildings, roads, and other impenetrable hard surfaces, resulting in urban flooding giving rise to another set of challenges. This makes rainwater harvesting even more essential and advantageous. Urban flooding on one hand, and increasing water shortage on the other, is the driving force behind government norms to inculcate the culture of rainwater harvesting in more and more cities.
Let us take the case of Mexico City as an example. It is a city with one of the highest demands for water in the world. Today it is plagued by drying aquifers, the city to sink to the earth by 50 centimeters per year. Today it is estimated that while a large volume is lost every way on account of leaking water pipes across the water management system, heavy rains cause heavy flooding that leaves substantial damage behind every occurrence.2 Researchers confirm that if the city was to adopt an effective rainwater harvesting system, 60 percent of the city's water needs could be met.3 In light of this, Isla Urbana, a local non-profit, has installed 20,399 rainwater harvesting systems from 2009 to date. The systems have recorded a harvest of 815 million liters annually.4 Mexico City's water authority, SACMEX, has also installed rainwater harvesting systems in 85 schools in the Tlalpan and Alvaro Obregón boroughs.
Likewise, India — a country that can collect up to 1,000 liters of water or even more during the heavy monsoons — has shown a similar response. In the southern state of Kerala, the government has recently constructed around 87,000 rainwater harvesting pits across schools, offices, and residences,5 with the expectation of these pits to last up to five years, with minimum maintenance.
Following the trend, Singapore installed a rainwater harvesting system on the roof of a 15-story skyscraper. The system diverts the rainwater collected on the roof to two rainwater tanks. This water is supplied to the building’s toilets, with no processing or treatment — a demonstration of how a project like this can be successfully implemented in metropolitan cities such as New York with countless high-rises to cater to their equally high water demands (981 million gallons consumption per day, as of 20206).
But New York is hardly a city to miss out on the ongoing trends. NYC’s Department of Environmental Protection recently initiated a Rain Barrel Giveaway Program as part of their $2.4 billion Green Infrastructure Plan. Its objective is to encourage citizens to capture stormwater before it flows into the sewer system. The intention being to reduce sewer overflows into local waterways by 2030.
The world is slowly but surely waking up to the fact that rainwater harvesting systems need to be an essential part of the infrastructure. Irrespective of the intricacies, all rainwater harvesting systems require five fundamental components:
Catchment – The surface to collect rainwater. It could be a rooftop, a paved flooring surface, or a landscaped region. The volume of water you harvest is a function of the surface area of the catchment.
Gutters and conduit Pipes – They are responsible for directing the water to the storage tank. The most widely used materials for these are half-round pipes made of galvanized iron (GI), steel, aluminum, and uPVC, with GI, steel, and aluminum being the preferred options. Lead and other metal gutters (GI and steel) are not a wise choice for potable water systems. The slightly acidic quality of rain can dissolve lead and other heavy metal contained in gutter solders, contaminating the water supply.
The safest option to get the most usable rainwater is uPVC Pipes. They deliver faithfully on the promise of:
- water with no harmful metals lacing it;
- no leakages on account of corrosion over the years;
- their almost frictionless surface allows for the maximum quantity of water to flow to the storage system;
- their lighter weight allows for installation virtually anywhere.
Filters and first flush devices – Investing in the correct filtration device is a must. The filtration system should be one that can effectively remove harmful and polluting contaminants. A first flush valve flushes out the first spell of rain, which carries relatively more toxins from the catchment surface and air.
Storage tanks – An important component of the system. Depending on the space availability, they can be overhead, underground, or stacked. Common materials used for these tanks are poly, galvanized steel, and concrete. If the tank is above ground, measures to prevent algae growth will be needed.
Delivery systems – Piping systems that deliver the stored and filtered rainwater until the point of use. The material of pipes used for this purpose is the same as that of conduit pipes. uPVC pipes present the best option to deliver quality water consistently over the years. With 50+ years of life, no rust, no corrosion, no heavy metals, and an almost frictionless surface, they offer a perfect solution. High-quality uPVC pipes assure you of a leak-free, durable, and minimal maintenance delivery system.
While building a rainwater harvesting system or incorporating it in a facility, it is crucial to be careful while choosing the components for the solution. It is crucial to pick the right materials. The choice at this stage will define the efficacy of the solution and yield the desired results. Rainwater harvesting, if done right, can help the world tide over the water crisis, allowing us to leave a more beautiful world for your future generations.
Saumya Jain is Chairman of Vinyl Tubes Private Limited (Vinyl Pipes – www.vinylpipes.com), one of the most trusted brands in uPVC pipes. Since taking the helm as Principal Partner in 2013, he has been aligned to the company mission of getting drinking water to as many as possible and positioning Vinyl Pipes as one of the largest suppliers of uPVC pipes in the world.
References
1. https://www.worldwatercouncil.org/en/water-crisis
2. https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JB020648
3. https://rotoplas.com/sustentabilidad/rtp_resources/AR_ROTOPLAS_13mayo_pages.pdf
4. https://islaurbana.org/
5. https://www.thehindu.com/todays-paper/tp-national/tp-kerala/rural-areas-fare-better/article18407059.ece
6. https://www.nationalgeographic.com.au/engineering/top-10-green-buildings-of-2017.aspx