Do you want to use rainwater to help the environment and your water needs at the same time? Well, you have landed at the right place as here we’ll be discussing rainwater harvesting and its types in detail.

Rainwater harvesting is the collection and storage of rainwater for present and future use. It is one of the most simple and effective ways to conserve water in a time where water shortages are becoming sevre.

Water crisis in India is rising monstrously and cities like Chennai and Mumbai are facing the worst of it. To quench Chennai’s thirst, seasonal water trains are now required. This situation makes rainwater harvesting a necessity. 

In this article, we will discuss the various types of rainwater harvesting but before that let’s understand the working of a rainwater harvesting system

Working Of A Rainwater Harvesting System

A rainwater harvesting system collects rainwater accumulate in large surfaces like roofs and balconies, and stores to satisfy your water needs.

Here’s an image of a rainwater harvesting system:

CC: Panchkula

As shown in the image, rainwater falling on the roof is directed to the tank and used for various purposes. The water entering the tank is filtered and excess water goes to a well.

Let us discuss each component and its function in a rainwater harvesting system in detail:

1. Catchments (Terrace or Courtyard of Building)

The catchment of a water harvesting system is like a big sponge that soaks up rainwater. It’s the surface where rain falls and gives water to the system. This surface can be anything, like a paved area such as a terrace or courtyard of a building. Even a roof made of strong materials like cement or metal sheets can be used to collect water for harvesting.

2. Gutter or Collection Pipe

To collect rainwater from a sloping roof and store it, you can use channels called gutters. These gutters can be simple PVC pipes. It must be suitably located to ensure maximum harnessing of rainwater. And make sure the gutters are a bit bigger than needed to handle heavy rain.

3. First-flushing

A first-flush device is like a special valve that makes sure the initial rainwater, which often carries more dirt and pollutants from the air and surfaces, doesn’t go into the water system. When it first starts raining, this valve helps flush out the not-so-clean water, keeping the collected rainwater cleaner and safer for use.

4. Filter

A simple sand and charcoal water filter is an uncomplicated way to clean water. This filter is made with layers of gravel, sand, and charcoal, etc. These materials work together to remove impurities from the water, making it safer and better to drink.

5. Main Tank

Main tank is the primary location for storage of rainwater. It is usually an underground cemented tank with connections to entire system. 

These tanks require a good amount of maintenance to prevent contamination. Frequent monitoring of water level is also required. 

The monitoring of water level can be effectively done using Flotaa. Flotaa doesn’t just monitor water levels in a tank but also keeps you posted via mobile app.

6. Pump

A pump is a basic requirement to distribute water to various utilities from the tank. A pump is imperative in rainwater harvesting systems which have an underground tank.

The pumps used in a rainwater harvesting system must be extremely durable. This is because they might require constant switching and sometimes have to run dry for a while if the consumer doesn’t know that the tank is empty.

Using Flotaa can significantly boost the lifetime of your pump and even automate the entire system.

7. Distribution Pipes

Distribution Pipes transport the water from the main tank to utilities or well. These pipes must be leakage free and sturdy as high pressure water from the main tank’s pump flows through them.

They must have valves to ensure there is no negative flow of water as it may contaminate the entire system due to direct connection with the main tank.

8. Well or Recharge Pit

In case the tank is filled up, water is sent to underground wells which not only store water but add to the ground water. 

Water in the recharge pit can also be utilized in future if need be as dispersion of water to the ground may take a good amount of time.

9. Controls

Rainwater harvesting systems can also contain a control panel, allowing users to visually inspect and monitor the system. 

This helps users identify potential issues. To address situations where users might not be aware of faults, control panels should incorporate alarms for common problems, ensuring the system’s smooth operation.

Types of Rainwater Harvesting Systems 

Rainwater harvesting systems are classified on the basis of pumping mechanism and storage tank. Let’s discuss them in detail:

1. Water Butt

The most basic way of harvesting rainwater is the simple garden water butt. Water collects from drainage pipes during natural rainfall, the water is mainly used to grow garden vegetables, car washing and other such purposes. 

Users having small gardens will benefit a lot from it. Implementing a rainwater filter along with the water tank will only add in to quality of harvested water making it suitable for various other chores.

2. Direct Pumped

A direct pumped rainwater harvesting system is of two types:

1. Submersible

A submersible pump is used to pump the water out of the rainwater harvesting tank. This pump is a part of an easy to install rainwater harvesting system for domestic and small commercial properties.

If the tank is about to run out of water, mains water must be supplied from time to time in small quantities. This process can be entirely automated using Flotaa.

This system is capable of supplying water to washing machines, toilet cisterns and similar other utilities.

2. Suction

This system uses a suction pump installed in the house of the user. Since the filter and pump are not in the tank, cleaning them is much more easy.

The back up from the mains is also taken in by the suction pipe and therefore there is no necessity of diverting water to underground tank through main.

In uses and application, a suction pumped rainwater harvesting system is similar to a submersible system.

3. Indirect Pumped

An indirect pump based rainwater harvesting system uses booster pumps to supply water. The tank can be located and any level as the booster pump provides the required pressure and flow. It is mostly used in multi-storey buildings and commercial complexes.

The water can be used for almost all the chores except drinking. The tank in this case too, needs to be filled with mains water if the rainwater is about to run out. Again, this large scale process can also be automated using Flotaa.

4. Indirect Gravity

In the indirect gravity kind of rainwater harvesting system, pumped water is used for filling up the header tank. Then, the water is fed into the outlets by using gravity.

In this system, the pump operates only when the header tank needs to be refilled. The mains water is piped into the header tank and not to a harvesting tank. Using a filter between the header tank and harvesting tank can make the water fit for drinking too.

The main advantage of this system is that it does not let the mains water become impure due to impurities in rainwater if a filter or treatment is used.

5. Gravity Only

Gravity only rainwater harvesting system does not use pumps and works on gravity alone. The tank sis built at a higher level than the outlets but lower level than gutters.

As this type of rainwater harvesting system uses gravity to transport the outlets, it is a very energy-saving option.

This system is mostly used in rural areas to irrigate the land and other farming purposes. The water is not fit for human-contact chores.

6. In-Ground Storage

In-Ground Storage rainwater harvesting system uses an underground tank for storing rainwater. They are mostly used in areas of single season rainfall. 

An electric pump is connected to these tanks to pump out the water for effective use. The loss due to evaporation is less as the tank is insulated underground. Also, water in these tanks does not freeze below the frost line.

The water from this system can be used for all household chores and even drinking if a filter is added to the system.

7. Retention ponds

Retention ponds are used to collect surface runoff water. The bottom of the ponds is either covered with mud or lined with concrete. Instead of filter,this system purifies water by natural processes like:

1. Sedimentation
2. Decomposition
3. Soil filtration
4. Solar disinfection

The main uses of this water are livestock watering, irrigation, groundwater recharge, etc.

Conclusion

Most of the perennial rivers in the southern part of the country have dried up. Should we now wait for the Ganga to dry? 

Harvesting rainwater not only conserves water but also saves a lot on your water bill. It is easy to install and rather inexpensive. With the knowledge that this article furnishes, we hope you will contribute towards making earth a better and a more watery place.

Frequently Asked Questions