Rainwater and Rainwater Harvesting – A Useful Summary

The belief in Rain-gods in ancient times, in almost every culture of the world, is the sign of the significance of rain, for the earth. We all are aware of the strength of the rainwater and have learned to respect it in all possible ways. Harnessing the rain with rainwater harvesting systems, or any other known storage method is our way of using each drop of the rain to its full potential. It is the need of today’s time to conserve the offerings of nature; conserving rain is one of that precious upkeep. This blog intends to summarise the quality use of rainwater and the basics of rainwater harvesting.

“A single gentle rain makes the grass many shades greener”

– Henry David Thoreau

   An American Philosopher

As believed, life on the earth began in the water. This has a huge impact on the way we interact with water in our daily lives. The rain is the primary source of maintaining hydrological balance on our planet. Hence, keeping a direct touch with the rain can benefit living organisms on multiple levels.

Rainwater has life-sustaining elements. Any imbalance of quality or quantity in rainfall, caused by human activities can have dreadful results. Having said that, the countries around the world are focusing on conservation of rainwater. The various methods of rainwater harvesting, the legislation passed for compulsory installation of rainwater harvesting systems, the awareness program run at the national and local level, are doing their bit in the revolution.

Let us go steady to understand rain and rainwater harvesting in India.

Composition of Rainwater

The constituents of rainwater are built primarily by dissolved particulate materials from the upper troposphere and secondarily by dissolved gases. Rainwater compositions vary largely as per the geography of the place; the rain near coastal regions have salt content and CO2 as Bicarbonate anion (acidic pH).

Even though rain absorbs gases and pollutants from the atmosphere, it gets pure as it reaches the earth’s surface.

Nutrients and Vitamin found in Rainwater

Rainwater is very good for plants as it contains a lot of nutrients. It is slightly acidic, naturally, which helps in maintaining pH balance. It is believed that rain contains vitamin B12. It is true but rain does not inherently contain Vitamin B12.

Giselle Brand, Clinical Dietitian at The University of Sydney states, “Many microorganisms that occur naturally in nature can produce vitamin B12. Rainwater is not pure water.” According to Giselle, with the rainwater falling through the air and washes down rooftops, microorganisms can get caught up inside it and Vitamin B12 can be produced as a metabolic by-product by these organisms.

The soil runoff contains the highest concentrations of Vitamin B12, according to Bruce C Parker of the Department of Botany, University of Washington, St Louis, Missouri.


Components of Rainwater Harvesting

The rainwater harvesting is an age-old inspired method of collecting and storing pouring rainwater. The ancient rainwater conservation techniques used in India, like the construction of the Jahalra, Bawari, Baoli ( for example Agrasen ki Baoli, New Delhi) and others provided the base for the modern rainwater harvesting techniques.

In the present world, we have more solid structures made up of steel and iron which are clubbed with a systematic and compact organization of conduits and other useful parts for collecting, transporting, filtering and storing of rainwater.

Every rainwater harvesting system contains 5 basic components:

  1. Catchment – A rooftop or a paved flooring surface or a landscaped area can be a catchment for the rainwater harvesting system. These are the areas where pouring rain is collected. Their surface area is calculated in square meters.
  2. Gutters and Down take pipes – the components are used to transport water from catchment surface to storage tanks. Generally, PVC or FRP rooftop rain gutters are installed due to their anti-corrosive properties.
  3. Filters and first flush devices – Rooftop or catchment surface filters are used to prevent grit, leaves, and dirt from entering the gutters or down take pipes. Additionally, a first flush device can be installed to divert the water from the first rain which accompanies great amount of pollutants, from entering the storage tank.
  4. Storage tanks – The over-the-ground or underground concrete or plastic tanks for storing the collected rainwater.
  5. Delivery systems – This includes piping systems that convey the stored rainwater to the point of end-use.

This stored water is fit for the purpose of gardening, vehicle washing, floor cleaning, and toilet flushing. If the intention is to use the harvested rainwater for drinking, cooking, and dishwashing, additional components and methods would be needed for the purification of the water. A submerged water purification filter can be inserted in the tanks. You can read our blog for more methods of converting rainwater into potable drinking water.

Legislation in the Indian States for Compulsory Rainwater Harvesting Practices

Central government bodies like Central Ground Water Board (CGWB), Ministry of Rural Development, Ministry of Water Resources, National Rainfed Area Authority (NRAA), The National Commission on Agriculture and many state authorities work in unison to spread awareness about the rainwater harvesting needs and methodologies. Not only this, the government legislation has been passed for making rainwater harvesting a mandatory practice for new constructions, in certain states.

In Himachal Pradesh, all commercial and institutional buildings, tourist and industrial complexes, hotels etc, existing or coming up who have a plinth area of more than 1000 square metres have a mandate  for rainwater storage facilities commensurate with the size of roof area. Similarly, other states like Ahmedabad, Bangalore, Port Blair, Chennai, Kerala, New Delhi, Indore, Kanpur, Andhra Pradesh, Tamil Nadu, Haryana, Rajasthan, Mumbai and Gujarat have implemented the same legislation, with some variation in required surface area. There has been a tax rebate of around 6 percent on property tax, in certain states like Madhya Pradesh, on the installation of a rainwater harvesting system.

Applications of Rainwater Harvesting

The use of rainwater has many effective implications as it is soft water. For instance, when used, rainwater doesn’t form scales on surfaces or utensils. It also lathers well with soaps and detergents. Other than this, on a larger scale, here is how rainwater harvesting proves beneficial:

  • It can reduce soil erosion around downspouts and in gardens.
  • It can control stormwater runoff.
  • It helps to control floods, in certain areas.
  • Reduces water bills and helps in optimum use of resources.
  • Reduces the demand for groundwater, hence help in sustainable replenishment of water beds.
  • Helps in nutritional plant growth.

Rainwater harvesting is no more an alien practice. This and all our blogs might help you to carry out rainwater harvesting, at the individual and community level. Remember, this can be your first step towards a better living planet, for present and all the future generations.

Things You Can Ask Chaitanya

Chaitanya Rain Harvest Products & Systems Pvt. Ltd. is a well-established engineering firm specialized in providing rainwater harvesting products and services. Our team consists of rainwater harvesting survey engineers, product consultants and installation engineers. You can contact us with the following or more relatable queries:

  • What capacity of a storage tank is needed at my premises?
  • Gravel size needed for groundwater recharge structure, in my field?
  • Is my premise feasible enough for installing a rainwater harvesting system?
  • How deep and to what capacity borewell can be dug at my farm?

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