What Is Rainwater Harvesting? Advantages And Disadvantages

. 10 min read
What Is Rainwater Harvesting? Advantages And Disadvantages

Table of Contents:

1. What Is Rainwater Harvesting?

2. How To Start Rain Water Harvesting Business In India?

3. Techniques Of Rainwater Harvesting

4. How To Start A Rainwater Harvesting Business?

5. Advantages And Disadvantages Of Rainwater Harvesting

6. Steps To Get Your Rainwater Harvesting Business Off The Ground

7. How To Create a Rainwater Harvesting System?

As urban expansion continues at a high rate, many local government agencies have decided to mandatorily adopt rainwater harvesting as a bid to combat water shortages. Increasing urban populations and uninhibited development has put hitherto unseen pressure on existing infrastructure and resources. One of the biggest hit resources of most urban developments is the availability of freshwater, a basic necessity for human existence. The rate of the growth in demand for fresh water in urban areas is about four times that of rural areas. Rainwater harvesting is seen as one of the best practices to combat the ever-rising issue to supply to clean water. The main advantages of rainwater harvesting systems include conserving water resources and the environment, pollution reduction, controlling flooding, and the reduction of the impact of climate change.

1. What Is Rainwater Harvesting?

Rainwater harvesting is a millennia-old technology where rainwater is collected, sometimes treated, and then used for various purposes. Today, with new technologies, rainwater harvesting has taken on a new and necessary function of being a solution for a lack of potable and non-potable water.

A rainwater harvesting system consists of different elements at different stages. Rainwater harvesting technology depends on the economic capabilities of the nation-states. However, the common components include:


Catchment is the first area that directly receives the rainwater. This can mean the roof of a house, its terrace, a lawn, road surfaces, or even pavement. An efficient water harvesting system must have a good catchment area to collect the maximum rainfall in a region.


The water from the catchment area must then be transported efficiently so that there is no loss of water. The transportation system includes gullies, traps, drains, pipes, and gutters. The size of the channels must be designed according to the rainfall the region receives. For example, a water harvesting system in a semi-arid region like Gujarat will require smaller channels than a region with high rainfall like Kerala.


The collected rainwater must then be filtered to remove debris and other pollutants. The water is run through a filtration system before reaching the storage chamber of the unit. There are many different types of filtration systems used based on the use of the harvested water and the region it is collected from.


The harvested and filtered water can then be stored in tanks or chambers or used for recharging the earth’s groundwater. In many cases, both types of storage can be designed. Recharging the groundwater can be done through various techniques from repurposing old wells to using state-of-the-art injection wells. The technology used will depend on the use of the water and the conditions in the region.

Limitations Of Rainwater Harvesting

2. How To Start Rain Water Harvesting Business In India?

Before you get into investments you have to understand rainwater harvesting importance alongside the limitations of rainwater harvesting firsthand. Let us see the other prime steps involved in rainwater harvesting:

  • To prevent groundwater deterioration and expand the groundwater index.
  • To improvise the quality of water in aquifers.
  • To preserve surface water flow during the monsoon season.
  • To diminish soil corrosion.
  • To instil a culture of water conservancy.
  • It aids you to cut down your water bills (especially in metropolitan cities where people must purchase water)

3. Techniques Of Rainwater Harvesting

The Government of India suggests two techniques of rainwater harvesting.

Surface Runoff Harvesting

Surface runoff is rainwater that flows away as runoff that can be stored for future use. It can be collected by diverting the flow of rainwater on roads, roofs and pavements into tanks above or below ground. The water can be used for general domestic use, gardening, and washing. Urban areas are perfect for collecting surface runoff since most surfaces are not porous and do not allow rainwater to be absorbed by the ground.

Groundwater Recharge

Groundwater recharge uses a process where the water moves downward. This is known as a hydrologic process. The surplus rainwater is used to recharge the groundwater through various artificial recharge techniques. Most urban areas, with their loss of green cover and excessive development are facing a crisis of depleted groundwater systems. From 2007 to 2017, the groundwater systems in India have depleted by 61%.

Rainwater can be used to recharge groundwater systems through:

  • Gully plug
  • Contour bund
  • Dugwell recharge
  • Percolation tanks
  • Check dams
  • Recharge shafts

4. How To Start A Rainwater Harvesting Business?

As with any other business, you will need to draw up a business plan for a rainwater harvesting business. You can decide if you want to rent a place for the business or set it up out of your house or any existing premises you may have. There are many governmental licenses and permits you will have to apply for before being able to run your business. It is best to hire a seasoned accountant and lawyer to help get the same.

The next step is to ensure that you have an efficient design team that can plan a good rainwater harvesting system for your clients. Conduct some market research and look at what you competitors are offering. You will also need a technical team with expertise in outfitting the system for your clients. Once you have the right personnel in place, you can then focus on marketing and then putting the word out about your business.

5. Advantages And Disadvantages Of Rainwater Harvesting

Now that we have understood all about what is rainwater harvesting importance, it's time to look at What are the advantages and disadvantages of rainwater harvesting?

What Are The Advantages Of Rainwater Harvesting System?

These are the benefits of rainwater harvesting system are:

  • Low cost.
  • Raises both water and energy preservation.
  • Reduces imported water needs.
  • Helps in water bill reduction.
  • Promotes the decrease in water demand.
  • It's an outstanding reservoir of water for landscape fertilisation with no chemicals and liquefied salts and unfettered from all minerals.
  • Eliminates the need for a filtration system for landscape irrigation.
  • The quality and quantity of groundwater are improved.
  • Relatively simple technology that is easy to operate and install.
  • Rainwater harvesting reduces- stormwater drainage, flooding, Soil erosion, along with the contamination of surface water with composts, pesticides, alloys and other debris.

What Are The Disadvantages Of the Rainwater Harvesting System?

Below are the disadvantages of the rainwater harvesting process:

  • Unpredictable rainfall patterns.
  • Lack of availability of proper storage system.
  • Needs regular maintenance.
  • Technical skills required for installation.
  • If the installation isn't done correctly, it will be prone to waterborne diseases and attract mosquitoes.
  • It is limited and no rain can restrict the stock of Rainwater.

6. Steps To Get Your Rainwater Harvesting Business Off The Ground

Apply for the required governmental licenses through accountants and lawyers. Initially, you will need a small design team of 4-5 people who understand rainwater harvesting systems.

Understand the price point of the various systems available based on competition driven market pricing. As of October 2020, this is approximately 4.5 lakh per year with a total scope of harvesting 170,000,000 liters of rain water.

You should decide if you want a storefront or if you can base your operations either at home or any other premises you may own. The rent for your storefront will factor into your overall expenses.

Prepare the capital required for setting up the business. A small scale residential rainwater harvesting system can cost between INR 2,000 - INR 30,000 per 300 sq. m. This might mean saving up, looking for investors, or seeking out loans.

Understand your operating costs, which includes soil testing, soil excavation, brickwork, concrete costs, and more. Here is a table to help you understand the basic capital required, the unit it is measured in, and the price of each step.

Project Stage Unit Cost (INR)/Unit
Soil Excavation CU. M. 90.00
Rock Excavation CU. M. 150.00
Brickwork w/ Cement Mortar (1:6 ratio) CU. M. 1400.00
Plain Cement Concrete (1:3:6 ratio) CU. M. 1500.00
Reinforced Concrete (Cement, Steel Bars, Shuttering) CU. M. 4700.00
PVC Rainwater Pipes (Piping Included, 110mm and 200mm diameter pipes) Meter 110mm - 165.00200mm - 275.00
150mm Diameter PVC Casting w/ Borehole on Soft Soil Meter 180.00

Also read: Water Tank Manufacturers in India

These prices do not include rooftop rainwater harvesting systems which can vary based on the system used, the area, the tank, and the design. Prices also vary immensely based on availability of material and cost of skilled labour. Prices for residential systems and commercial systems vary based on the quantity of harvesting required and the systems used.

Advantages And Disadvantages Of Rainwater Harvesting

7. How To Create a Rainwater Harvesting System?

Check the roof surface first. It could be a sloping or flat roof which will need special systems to collect the water. You will need to install durable gutter meshes to prevent blocking from leaves and other debris. The gutter outlets should be installed correctly. A first flush water diverter will prevent the first rains from being collected in the tanks. This is important since the first rains are usually the most contaminated.

Select the right size of water tank. You will have to base this decision on the annual rainfall of the region, the size of the roof and the use of the water. Install a tank screen to keep mosquitoes and other pests out of the tank. Install a pump system to distribute the water inside and outside of the premises. Install a filter to reduce residual sediments, colour, and odour. Install a water level indicator to monitor the water collected and used.

Although rainwater harvesting is a desirable concept that has seen much traction in the past decade, it hasn’t seen too many takers in rural India. About 81% of all groundwater is used for agricultural usage. This shows us that rainwater harvesting is of essential need for our farmers. Even Prime Minister Modi has mentioned that we are using only 8% of our rains. The Government of India has started many initiatives around rainwater harvesting with attractive subsidies. A good rainwater harvesting business must take advantage of these schemes and provide the best service to their clients.

We hope our article turned out to be useful for you. For more such informative content, you can visit these linked articles as well:
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Q. What are the benefits of rainwater harvesting?

Ans: The advantages of rainwater harvesting system are:

  • Does not need a high initial investment.
  • It can help reduce the water bill.
  • Decreases the demand for water.
  • Reduces the need for imported water.
  • Promotes both water and energy conservation.
  • Improves groundwater systems.
  • Does not require a filtration system for landscape irrigation.
  • The technology is relatively simple and is easy to install and operate.
  • It helps reduce soil erosion, stormwater runoff, and flooding.

Q. What are the different methods of rainwater harvesting?

Ans- The different methods of rainwater harvesting are as follows:

  1. Filter
  2. Catchment
  3. Transportation
  4. First, flush
  5. Rooftop rainwater harvesting
  6. Surface runoff harvesting

Q. What is the importance of rainwater harvesting?

Ans- Rainwater(s) harvesting importance lies in its sustainability of preserving water for future needs. With the current global warming situation, this method will help develop a good source of water for the future.

Q. Is rain water harvesting expensive?

Ans- It depends on the availability of water along with the storage space you have around you. Other structures like tanks and wells can be modified for water harvesting. For buildings of about 300 sq. feet, it would typically cost around 2 to 3 thousand rupees.

Q. What are the uses of rainwater harvesting system?

Ans- These are the primary uses of rainwater harvesting system:

  • Composting
  • Fire Protection
  • Equipment washing and vehicles
  • Cooking
  • Agricultural purposes
  • Water for pets, livestock, wildlife
  • Pools and other water bodies
  • Outdoor plants, House plants and Gardens
  • Drinking
  • Vegetable Washing
  • Toilets

Q. What is rainwater harvesting in general terms?

Ans- Rainwater harvesting is a sustainable method to gather and store rainwater for reusing it in the future. This helps save a lot of rain water from getting run off to waste.