We all know that around 73% of the surface of our planet is covered by water, yet only 2% of that water is freshwater. In Asia, 8% of the continent’s freshwater is used for industry, 6% for personal usage, and 86% for agriculture. For agriculture, India uses 83% of the freshwater available. Since it is an essential natural resource for sustaining life on Earth, water is regarded as the foundation of all life. Being a valuable natural resource, Rainwater Harvesting is important to our daily existence.
It is undeniable that water conservation has a positive impact on maintaining a sustainable ecosystem, especially as the urgency to combat climate change grows. Fresh water is primarily obtained from groundwater. Over the past few years, there has been an upsurge in water scarcity in many places of the world. To reduce the high loss of water rate, ideal measures should be adopted in place. People must be aware of the water shortage that we are currently facing. The water issue can be resolved using a variety of methods. One technique for water conservation is the Rainwater harvesting method.
Rainwater harvesting is a technique or approach for collecting rainwater and safely storing it for later use. As the effects of the climate crisis worsen and some regions of the world face groundwater depletion and freshwater pollution from seawater flooding, rainwater harvesting has become more and more crucial. Water can be collected from a variety of locations and surfaces and preserved for later use. Most of the time, hard surfaces like roofs and other ones are used to collect the water.
Objectives Of Rainwater Harvesting
Rainwater harvesting aims to stop the downhill water flow and control how it travels across the landscape. The objective of rainwater harvesting depends on the environment where the water will be used.
- To address the issue of inadequate water supply as well as the rising population’s need for water
- To raise the levels of subsurface water
- To make sure that water is used and stored sustainably
- Using dilution to enhance agricultural output and boost a specific area’s groundwater quality
- To enhance ecological harmony
Techniques For Harvesting Rainwater
In general, there are2 methods for collecting rainwater.
Surface runoff harvesting
The majority of precipitation that falls on areas either evaporates back into the atmosphere or is diverted into nearby rivers before it can be used. Yet, if the rain is captured using adequate facilities, it can significantly increase the amount of freshwater that is readily available for human consumption. Thus, surface runoff water harvesting is the process of gathering stormwater, storing it, treating or purifying it, and then reuse it later. In urban areas, the surface runoff water harvesting method is frequently used.
The technique can also make use of runoff from additional catchment areas, and man-made surfaces, such as roads, parks, and gardens. This approach can effectively a large amount of water if the right technique is applied. Typically, reservoirs with earthen bunds or embankments are excavated in the ground for the storage of the gathered water. Such reservoirs can be up to 12 ha in size.
Rooftop rainwater harvesting
The process by which rainwater is collected from roof catchments and stored in reservoirs is known as rooftop rainwater harvesting. By using artificial recharge techniques, collected rainwater can be stored in subsurface groundwater reservoirs to provide for the demands of the family through tank storage.
Making water available for future use is the primary goal of rooftop rainwater harvesting. If used correctly, this method, which is less expensive and very efficient, contributes to raising the groundwater level of the particular area.
Rainwater Harvesting: Types And Costs
The cost of Rainwater harvesting systems varies based on the size, sophistication, and difficulty of the installation. The goal of each system is to collect rainwater and use it within the building to reduce the need for water from the utility supply.
Roof stormwater can be collected using rain barrels. Usually, rainwater collected is utilized to water plants. A rain barrel system includes a screening lid to catch debris and a spigot or tap with a hose attached at one end for collected water supply, which can be used for gardening. A downpipe and rain gutters can be automatically filled with water by adding an overflow control to the barrels. Whenever the barrel is full, a diverter can be used to accomplish this.
You can direct the rainwater running from your home’s roofs to empty directly into a rain barrel of your choice using PVC pipes. Rain drums on the market are typically composed of plastic. For simple maintenance, make sure to select a rain drum with a removable cover.
Rain barrels can be as small as 50 liters or as large as ones with a capacity of 50000 liters. For domestic use, the former with less volume storage can meet the need, but the latter is chosen for commercial application.
A rain barrel with a capacity of 500 liters costs about Rs. 2500.
These reservoir tanks can be constructed of concrete, making them a permanent solution for meeting the needs of water harvesting at any time. Therefore, even though the upfront cost is a little higher than that of plastic rain barrels, considering the long term, this may be a better-fit alternative. Additionally, dry cleaning the walls to remove any algae growth is another suggested maintenance measure.
With this method, a reservoir can be used in place of a barrel to collect stormwater that is running down the roof. They have a larger capacity than barrels. Considerable choices include Ferro-cement tanks, reinforced masonry, PVC, and corrugated iron tanks. When considering the permanent concrete tank option, experienced people always advise considering the cost-benefit ratio. Another factor to consider is the roof’s slope and annual rainfall.
The main factor here is the type of substance used. A 5000-liter Ferro cement tank typically costs around Rs. 12000 in India. The quantity may be even lower with plastic tanks.
Rain Saucers and Rain Chains
Both options are ideal for a home rainwater collection system. Even in situations where there is little to no space for installing a full stormwater harvesting system, such as in apartments, rain saucers can help save rainwater. No connection to the roof or gutters is necessary.
A funnel, PVC pipes, and storage supplies like buckets are necessary for a rain saucer. These rain saucers are frequently paired with barrels. Rainwater collected in funnels can flow through pipes to the storage unit, which is located beneath. While rain chains and rain gutters work together to guide water flow to a storage container without additional wash away, runoff can therefore be conveniently moved from the collecting pipe to the drains by moving downhill.
It is usual to place rain saucers on top of plastic barrels or drums to collect rainwater. Due to their endurance and elegance, rain chains with copper basins and vertical tubes are highly favored.
Rain Saucers (Source YouTube – tspargo)
Online retailers sell copper rain chains starting at Rs. 2000 and rain saucers for less than Rs. 5000.
Rooftop Rainwater Harvesting
In terms of rainwater harvesting, rooftop water catchment combined with storage tanks can be advantageous. Additionally, the water may be deposited into below-ground reservoirs to be used for residential purposes later. The water thus saved is typically used during the dry season.
Because it is less expensive, a rooftop rainwater harvesting setup is favored in flats over surface run-off rainwater harvesting approaches. Rainwater is collected from roofs using PVC conduits and sent to sump tanks that have filters inside. Water is pumped to a borewell system or overhead tank through a pump. After being collected, the rainwater is put to use in a variety of ways.
The decision to install a rooftop rainwater harvesting system is very advantageous in towns with dense populations of villas and flats and high-water demands. One major benefit is that it can serve as a water reserve and stop floods during periods of heavy rain.
A single installation for a complete apartment complex, including filters, percolation pits, plumping, and storage tanks, can be done for as little as Rs. 30000 or less.
Components Of Rainwater Harvesting
A Rainwater harvesting system uses various parts to filter collected water, transfer it through pipelines or drains, and store it in tanks.
Rainwater Harvesting Catchments
Catchment area refers to the area that immediately gathers rainwater and supplies water to the system. It may be paved, like the terrace or courtyard of a structure, or unpaved line open space. Water can also be collected from roofs consisting of corrugated sheets, galvanized iron, or reinforced cement concrete (RCC).
It stops debris from entering the roof since it is there.
A sloping roof’s edge is surrounded by channels that collect and carry rainwater to a storage tank. Gutters are often fabricated locally from simple galvanized iron sheets and come in semi-circular or rectangular sheets. Gutters need to be held in place so that they won’t sag or collapse when filled with water. The construction of the house determines how gutters are attached; typically, iron or wood brackets are fastened to the walls.
Pipelines or drains known as conduits are used to transport rainwater from catchments or rooftop areas to harvesting systems. Conduits that are frequently purchased are comprised of materials like galvanized iron (GI) or polyvinyl chloride (PVC).
The majority of the dirt from your roof is carried away by the first rains, which is diverted by a first flush diverter, a device, or piping assembly. In general, the quality of rainwater that enters the storage tank or recharge zone improves the more water is redirected.
Rainwater collected from rooftops is filtered to remove suspended contaminants. The several types of filters that are typically used for commercial purposes include slow sand filters, charcoal water filters, and sand filters.
Rainwater Harvesting Storage Facility
Regarding the form, size, construction material, and placement of the tank, there are several possibilities available, including the following; –
Shape: Rectangular, square, and cylindrical.
Construction materials include masonry, reinforced cement concrete (RCC), Ferrocement, etc.
Tank Placement: These tanks can be built above ground, partially underground, or completely underground, depending on the amount of available land space. To guarantee the quality of the water held in the container, several upkeep procedures like cleaning and disinfection are necessary.
Rainwater Harvesting Recharge Structures
Through appropriate structures like dug wells, borewells, recharge trenches, and recharge pits, rainwater harvesting can also be used to top off groundwater aquifers. Several different recharge structures can be used; some facilitate the percolation of water through soil layers at lesser depths (such as recharge trenches and permeable pavements), while others carry water to deeper levels before it reaches the groundwater (e.g., Recharge wells). It is not always necessary to build new buildings because existing ones, such as wells, pits, and tanks, can be converted to serve as recharge structures. Settlement tanks, recharging of service tube wells, recharge pits, recharge troughs, recharge trenches, and modified injection wells are a few of the commonly used recharging techniques.
Benefits Of Rainwater Harvesting
The fundamental advantage of rainwater harvesting is that it is an environmentally friendly method of managing water that everyone may utilize at different levels, from a basic rain barrel to a sophisticated system that connects to an irrigation system or domestic plumbing. The practice of Rainwater harvesting I thought to be self-sufficient, socially acceptable, and environmentally responsible.
Simple to maintain
The community gains a few benefits by using the rainwater harvesting system. Very first, collecting rainwater improves how efficiently we use an energy source. Since drinking water is not readily replenishable, it is crucial to take these steps to reduce wastage. Systems for collecting rainwater are based on basic technology. Compared to water purification or pumping systems, the total cost of installation and operation is significantly lower for these systems. Little time and effort are needed for maintenance.
Independent water supply
Rainwater harvesting provides a dependable water source in places where getting access to clean water is expensive or challenging. Rainwater harvesting improves the amount of drinking water that is accessible and is a crucial source of clean water.
Save money on water bills
There are various non-drinking uses for the water collected by the rainwater collection system as well. This results in a significant decrease in utility costs for lots of homes and small companies. On a large scale, collecting rainwater can supply the water required for numerous operations to run smoothly without depleting local water sources.
Ideal for Irrigation
The water that is collected is excellent for agricultural use since it lacks the contaminants that are present in most groundwater sources. Furthermore, limiting runoffs during intense rain also lessens soil erosion and flooding. Since they will eventually be less contaminated, lakes and rivers will gain from this.
Use less groundwater
The need for water is always growing along with the population. As a result, many industrial and residential communities remove groundwater to meet their daily needs. As a result, certain locations with extreme water scarcity have seen a dramatic decline in the amount of groundwater.
In times of drought, rainfall collected in previous months can be used. In dry regions, soil ridges are built to catch precipitation, stop it from pouring down hills and slopes, and improve irrigation. There is always enough water gathered to support agricultural growth, even during dry times.
Flooding and soil erosion is reduced
Large storage tanks are used to collect rainwater during the rainy season, which also helps some low-lying communities avoid flooding. In addition to this, it aids in lowering soil erosion and the contamination of surface water with pesticides and fertilizers due to runoff from rain, leading to cleaner lakes and ponds.
Rainwater Harvesting for drinking
Rainwater maintains a healthy, livable environment. Additionally, salinity or contaminants in groundwater do not have an affect on rainwater. The rainwater can be utilized for drinking if it is collected properly using the appropriate technique and equipment.