Techniques of Rainwater Harvesting

Rainwater Harvesting is a growing practice here in the States, especially in arid areas of the Southwest where water scarcity is an ongoing problem but throughout the world, there are different techniques that bring needed rain to farms and wells that are crucial and life-threatening. What are some techniques of Rainwater Harvesting?

  • Well Recharging- H2O diverted to wells
  • Rooftop Harvesting-H2O diverted to tanks
  • Trench Recharging-trenches dug between crops
  • Soakway-H2O held in the upper layer of farm soil
  • Recharging Bore Wells-rain diverted to aquifers
  • Street Runoff Harvesting-rain diverted from streets
  • Percolation pit-H2O for gardens

Rainwater Harvesting is a practice that has been around for many years and is simply moving rainwater from an area that is abundant and moving or saving it for an area that is in need of it or is scarce.

Understanding the Importance and Methods of Rainwater Harvesting


Rainwater harvesting isn’t just a trend it’s a solution to the world’s water-related issues. Its importance can’t be overstated. This method involves the collection and storage of rainwater for various applications, and it’s an energy-efficient option that’s gaining traction across the globe. There are several rainwater harvesting methods involved, each providing distinct benefits.

Among the rainwater harvesting methods, there’s rooftop harvesting. This technique involves utilizing your roof as a catchment area. When it rains, the water gets directed into gutters that feed into a storage tank. A well-thought-out system like this can gather large volumes of water. Additionally, having a tank eliminates the occurrence of runoffs, which are a leading cause of soil erosion.

To properly comprehend the different rainwater harvesting methods, ground surface water capture can’t be ignored. This particular method capitalizes on rainwater that falls directly onto the earth’s surface. The rainwater is normally directed to a reservoir or tank for further use. It’s a technique that doesn’t place heavy reliance on complex systems.

Select rainwater harvesting methods employ the use of artificial recharge systems. These systems are designed to replenish groundwater supply directly from rainfall. The beauty of these systems is their ability to greatly improve the efficiency of the harvesting process. Redirecting rainwater through these systems can help alleviate water scarcity issues, especially in arid regions.

Rainwater harvesting doesn’t solely depend on system design alone. The application of various techniques and ways to heighten the efficacy of the harvesting process is key. Simple methods such as rain gardens and permeable surfaces provide a beautiful yet functional way of maximizing water collection.

Lastly, we must look into rainwater harvesting systems that use green roofs. This innovative technique enhances water retention while causing a reduction in stormwater runoff. Other benefits include thermal insulation and providing a habitat for wildlife. Here, the harvested rainwater can be stored in tanks and used for non-potable purposes, like irrigation and toilet flushing, or treated for drinking.

Harvesting rainwater is not just about the collection of precious commodities but also about the ingenious methods employed. From standard rainwater harvesting to more complex methods, all come with different measures of success and challenges. Regardless of the technique used, the fact remains that rainwater harvesting is indeed an imperative venture toward securing our water future.


 Introduction to Rainwater Harvesting and its Permaculture System


Rainwater harvesting, often shortened to “harvesting,” is an age-old practice that’s been around for centuries, and it’s under constant refinement and evolution. With today’s innovative technology, rainwater harvesting techniques have become more efficient and beneficial.

Constructing modern rainwater harvesting systems involve a methodical system design to optimize their effectiveness. A lot of factors are taken into consideration, including the roof’s surface area and material, the average rainfall duration, and the building’s daily water consumption.

One of the most common approaches is rooftop rainwater harvesting. Rainwater naturally runs off your roof when it rains, and this system captures the maximum amount of water possible. The rooftop collects the rainwater, which is then channeled into storage tanks via gutters and tubes, commonly known as feed systems.

But it’s not just about collecting the rainwater; you’ve to ensure that the water stored is safe for use. This is where the importance of quality construction of rainwater harvesting systems comes in, as they must be built in adherence to safety and cleanliness standards.

Depending on the design’s details, some systems may require a pump – referred to as a pumped system. These systems use power to move water from the rainwater storage tank to the household or garden. However, not all households need or can afford pumped systems.

In such cases, gravity-fed systems, where the water is essentially led to where it’s needed by gravity, can be a convenient option. Besides, they are less complex to set up and demand lesser maintenance two parameters considered in their system design.

A phenomenal method called permaculture, entailing the creation of sustainable and self-sufficiency-centered systems, has found immense application in rainwater harvesting too. In a permaculture system, the harvested rainwater nourishes the landscape, reducing the dependence on external water sources significantly, and ultimately saving resources.

For sure, understanding the ins and outs of rainwater harvesting system design can be a tad complex, especially from an outsider’s view. And that’s why many individuals and businesses resort to services offered by specialists in this niche. Remember, whichever design you choose, it’s crucial to ensure alignment with privacy policy norms, local codes, and regulations.

Overall, rainwater harvesting – be it rooftop rainwater harvesting or other methods – is a viable solution to today’s water shortages. A well-constructed rainwater harvesting system can save millions of liters of water annually, making a significant impact on our environment and promoting sustainable living.


Gravity Feed Techniques and Appropriate Pump for Rainwater Harvesting


Rainwater harvesting techniques are vital for both the conservation of water and for recharging the groundwater tables. One efficient method for this is through the design and application of the catchment area technique. Catchment areas are specific places where rainwater is channeled and collected, usually either on roofs or paved surfaces, offering a clean and efficient process for harvesting rainwater.

Upon using catchment areas, the gathered rainwater often needs filtration to remove debris before being stored in a tank. Filters play critical roles in ensuring the cleanliness of the rainwater. A rainy day can lead to an accumulation of dirty water without them, but filters can clean this water for later use.

The catchment area technique, which is highly reliant on the surface, the user is harvesting from, requires the concrete ground to be designed with a slight gradient towards the tank. This trench leading to the tank enables the rainwater to flow into it for storage or further filtering. A well-designed catchment area can maximize the collection of rainwater from each downpour.</p>

After filtering, the rainwater, ready for harvesting, is then stored in the tank. However, choosing the appropriate pump to transport the filtered rainwater from the tank for use or recharge can be a challenge. This is where the user must consider factors such as the size of the tank, the quantity of water it holds, and the desired flow rate.

Recharging groundwater is another essential aspect of rainwater harvesting. To facilitate this, techniques like recharge pits, recharge shafts, or even the simple design of a catchment area can be applied.

These methods enable the water collected in the tank to percolate into the ground. A recharge pit or shaft filled with layers of coarse sand and fine gravel help filter the water further before seeping into the groundwater table.

From a mobile or website, users can access further information on rainwater harvesting techniques. These platforms provide insights into constructing an efficient catchment area and choosing the appropriate pump. They offer detailed knowledge on designing and implementing recharge structures and understanding how to effectively filter and store harvested rainwater.

Whether you’re a novice at rainwater harvesting or have been practicing it for a while, the right technique, knowledge, and tools can make a significant difference to your efforts and contribute mindfully to the environment.

Rainwater harvesting (RWH) is the collection and storage of rain, rather than allowing it to run off. Rainwater is collected from a roof-like surface and redirected to a tank, cistern, deep pit (well, shaft, or borehole), aquifer, or reservoir with percolation so that it is capped off treated, and saved to be used on-site or seeps down and restores levels of the groundwater recharging water system in the area.


Well Recharging

It is a type of rainwater harvesting, in that the water which is collected during the rain storm is directly stored in the well. Later it can be used for domestic use.  Rainwater from the rooftop is diverted to drilled wells after passing it through the filtration bed. Cleaning and desalting of dug well should be done regularly to enhance the recharge rate.

A dug well can be used as a recharge structure. Rainwater from the rooftop is diverted to dug wells after passing it through the filtration bed. Cleaning and desalting of dug well should be done regularly to enhance the recharge rate.

The filtration method suggested for bore well recharging could be used.


Percolation Pit

It is a method of rainwater harvesting, that a pit of 1-2m wide and 3m deep is first dug. The bottom 50% should be filled with 40mm gravel, the middle 25%  of the pit is filled with 20mm gravel and the upper 15% will be filled with coarse sand. The remaining 10% is left open. On the upper later a plane brick is kept for a perfect water spread.  The stored water can be used directly for gardening and raw use. Percolation tanks should be built in gardens, open spaces, and roadside greenbelts of urban areas



Rooftop Harvesting 

This is a simple method of rainwater harvesting, that the rainwater is directly collected from the rooftop to the specified water tank for domestic usage.

How to build a Contour Bund/Trench in Hilly Areas for Rainwater Harvesting

Trench Recharging

Soakage trenches, also known as infiltration trenches or recharge beds, are excavated trenches wrapped in filter fabric and filled with coarse stone. Soakage trenches receive runoff via pipes and store it in the rock voids until it can infiltrate, or seep, into surrounding soils.

Between two trenches crops can benefit during the growing season (when there is less rain) from the subsoil water reserve gathered during the rainy season.

Soakway/Recharge Shafts

Soak-away or recharge shafts are provided where the upper layer of soil is alluvial or less pervious. These are the bored hole of 30 cm dia. up to 10 to 15 m deep, depending on the depth of the previous layer.

Bore should be lined with slotted/perforated PVC/MS pipe to prevent collapse of the vertical sides. At the top of the soak away required size sump is constructed to retain runoff before the filters through soak away. The sump should be filled with filter media.

Recharging Bore Wells

Rainwater collected from the rooftop of the structure is diverted through drainpipes to the settlement or filtration tank. After settlement, filtered water is diverted to bore wells to recharge deep aquifers. Abandoned empty bore wells can also be used for recharge.

Street Runoff Harvesting

Street runoff harvesting is a type of rainwater harvesting that takes advantage of the high volume of runoff that drains off paved and compacted surfaces of streets, dirty roads, driveways, and parking lots. Many of these concepts can also be applied to harvesting runoff from sidewalks and footpaths.



How Much Does a Rainwater Collection System Cost?

Starting with a DIY Rainwater Harvesting system:

$200.00-55 gal Drum-Diverter-Pump
$501 to $2,500-Drums up to 5,000 gals.
$2,500 to $12,000-above-ground 10,000 gal. cisterns
$12,000 or more high-end underground cisterns start around $12,000 & may go up to $22,000 with labor …………………………………………………………………….. Read more



Street Runoff Harvesting

Contour bunds are an effective method to conserve soil moisture in watersheds for a long duration. These are suitable for low-rainfall areas where monsoon runoff helps soil percolation along with crop production during dry seasons.


What is Rainwater Harvesting and the Best Way to Utilize Rainwater?

Rainwater harvesting is collecting the run-off from a structure and storing it for later use, typically rain will collect from a roof in gutters & then into a storage tank.
Providing free H2O for:

Drinking H2O
lawn & garden
Washing cars
Washing pets
Re-filling pools
Indoor toilets & washers
Fire Protection ……………………………………………………………………………………. Read more


JimGalloway  Author/Editor


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