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Everything You Need to Know About Trapping Rainwater


I've always had an interest in aquariums, aquaponics, and interconnected farming systems. I'd love to share with you the info I've learned.


The basic idea behind trapping rainwater is to collect it using existing structures. You can collect rainwater as soon as it touches the earth or the roof of your home. Hence, the collection area for rainwater may be either your backyard or the roof of your home.

Stored rainwater can then be used for household, industrial, and farming purposes. Furthermore, you can also utilize rainwater for drinking after passing it through a filtration system.

By taking advantage of rainwater, we can reduce the consumption of groundwater. Below are some essential aspects that you should know about trapping rainwater.

How to Trap Rainwater

Trapping rainwater doesn’t require any kind of additional structure. This is because you can use the roof of your home and its drainage system for this purpose. When talking about harvesting rainwater on an industrial scale, you may need some additional mechanisms.

After collecting the rainwater, you can keep it in rain barrels or large water tanks. These tanks would serve as the reserved water sources to meet your household demand. At present, a wide range of farmers and industrialists try to follow these energy-efficient and environment-friendly methods.

This approach not only helps us to utilize more of our natural resources—it also lowers the overall cost of farming or business. Hence, harvesting rainwater is the most viable and nature-friendly way to make use of available resources.

2 Different Methods of Collecting Rainwater

Although the basic principle behind collecting rainwater is the same, there are some differences regarding the scale of the collection system. To know how these methods affect the degree of actual water conservation, let’s take a look at them in detail.

Dry systems are usually used to store larger amounts of water, so they are often used in farms or facilities.

Dry systems are usually used to store larger amounts of water, so they are often used in farms or facilities.

Dry System

This method involves a variety of rain barrel setup that is much larger in scale than most. The volume of stored water is huge, so it requires more pipes and a larger collection area. The system is known as a “dry” system as the pipes are emptied into the underground tank and remain dry.

This system is typically used in setups that involve sizable underground collection units. These storage containers offer huge capacity, and you don’t have to worry about overflow. Moreover, with such a large amount of water available at your disposal, your reliance on tap water will minimize automatically.

Rain barrel systems work well for individual homes that don't need to store mass amounts of water.

Rain barrel systems work well for individual homes that don't need to store mass amounts of water.

Rain Barrels

This is a common method used by many homeowners. Within this system, the barrels are installed at the downspout of a drainage pipe of the gutter. The rainwater is collected within the barrel. You can either use a recycled or new barrel for this purpose.

Typically, the barrels aren’t that huge; therefore, these storage areas offer less water for domestic use. This kind of setup is suitable for areas that receive good rainfall. However, even if you don’t expect regular rainfall, constructing this system is beneficial in many ways.

The Stages of Rainwater Harvesting

When it comes to trapping rainwater, there numerous stages in the process. The first one is the transportation of rainwater through a system of drains and pipes. The next process is filtration and storage. Below, we explore the process of rainwater trapping in a comprehensive and easy-to-understand manner.

1. Catchments

This is the surface that is responsible for receiving rainfall. It serves as the first stage of rainwater trapping. Any paved area such as a roof, terrace, or courtyard of a building can be used for this purpose. For underground storage, you can also use unpaved areas such as open ground or backyard lawn.

2. Gutters

The channels that collect rainwater are called gutters. These drainage lines are attached to the lower end of a roof, where rainwater tends to drop. A sloping roof is the best option for this purpose, as the rainwater instantly rushes toward the gutters.

These gutters are linked to the pipes and storage tanks and are either rectangular or semi-circular in shape. However, in order to provide essential support to gutters, you must try to fix them with some secure attachments.

3. Conduits

These are the pipelines that carry the rainwater from a rooftop or catchment area and drop it into the collection unit. Mostly, people use PVC pipes to make conduits. This material is durable and easy to handle, which makes it an ideal material for this purpose.

4. First-Flushing

This system involves a valve that makes sure that the first spell of water coming through the drainage is flushed out. The basic goal of first-flushing is to prevent debris and pollutants from entering the storage system.

You can also store first-flushing water in a small tank and use it for purposes other than drinking. By doing so, you can utilize natural resources in a responsible manner.

Collected rainwater is usually filtered before being stored for use.

Collected rainwater is usually filtered before being stored for use.

5. Filter

This is the final stage of rainwater harvesting, which makes the water useable for drinking or other household purposes. It helps remove any kind of pollutants and suspended elements from the stored rainwater.

In most cases, the filter unit consists of different filtration layers. Layers include sand, charcoal, and gravel. These layers help to filter out unwanted materials like debris and dust before pouring the water into a storage tank.

Why Should You Use a Rainwater Filter?

The primary purpose of using a rainwater filter is to ensure that the collected rainwater is safe for household and drinking purposes. The first stage of filtration involves flushing out the first few liters of water that comes down from drainage pipes or gutters.

By using a typical filtration system, you can make rainwater as safe as drinking water. Hence, once processed, you can use this rainwater for the purpose of cooking and drinking. The rainwater may contain contaminants such as algae, bird excrement, air pollution, leaves, dust, and sand.

In order to make water suitable for humans, it is essential to install filtration and purification equipment. This system is capable of removing such contaminants and harmful elements.

Do You Need to Filter Rainwater to Drink It?

There is nothing purer than rainwater; however, air pollution can harm the purity of rainwater. Moreover, when rainwater falls on the roof surface, it is exposed to dust, debris, and bird excretions.

As a result, the rainwater also becomes contaminated, which makes it unfit for drinking. Therefore, the best way to utilize rainwater is to use a suitable and effective filtration system. After processing the rainwater through filters, you can remove all the contaminants and infectious elements.

Moreover, you can also use an in-house filter that purifies the water and makes it perfectly safe to drink. On the other hand, when you need water to wash your car or clothes, it isn’t necessary to use an expensive filtration system. You can use the collected rainwater after simply filtering it through a sand and charcoal filter.

Do You Need to Filter Rainwater to Grow Plants?

Although rainwater is ideal for plants as compared to underground water, the presence of pollutants is the main concern. Since our air is polluted with a variety of harmful substances like carbon monoxide, arsenic, and other acids, it is not advisable to use rainwater to grow plants without filtering it.

Acid rain is one of the issues, which may turn out to be harmful to the plants. Hence, before using rainwater for agricultural purposes, it would be better to use a proper filtration system. It will also ensure that the plants you grow are also healthy to consume.


Rainwater to Grow Food

When it comes to utilizing the rainwater for growing food, the first thing that comes into mind is the scale of such farming. In fact, the utilization of rainwater for agricultural purposes depends on the annual rainfall in a particular area.

For instance, if you live in an area that doesn’t receive sufficient annual rainfall, there is no point in creating a rainwater harvesting mechanism. The scale of water collection for agricultural purposes is larger than what we see in a household rainwater collection system.

In addition, the cost of making a rainwater harvesting system is enormous, which requires you to analyze the annual rainfall. If the rainfall in your area is good, storing rainwater for growing food is a viable method.

The most essential element necessary for plant growth is nitrogen, which is found in rainwater. When the water vapors condense, they absorb atmospheric nitrogen. This means that rainwater also minimizes the need for fertilizers.

Rainwater for Aquaponics

To run an aquaponics farm, rainwater would serve as the best option. This is because rainwater is fresh, clean, and soft, which makes it a perfect source of water. When you are harvesting rainwater for aquaponics, you need to offer some sort of filtration system to remove the impurities.

Moreover, the rainwater used for this purpose is recycled continuously. This suggests that if the water is fresh, there isn’t any issue of toxic run-off. Since there are no weeds, you don’t have to use harmful chemicals, pesticides, or herbicides.

Rainwater for Hydroponics

If you are looking for renewable energy and water resources, rainwater is the best option to consider. This alternative to tap water is more effective as it requires less energy and resources to store rainwater.

The best way to use rainwater for a hydroponics garden is to collect and filter the water before entering it into the system. Rainwater is soft, which assists the photosynthesis process for better growth hydroponic plants.


Rainwater for Greenhouse Plants

No doubt, water is a highly useful and precious resource for growing plants in any kind of setup. When you are running a greenhouse farm, it is possible to make it more efficient by using rainwater.

In most cases, greenhouses utilize drip irrigation, which makes it possible to use stored water for an extended time. The roof of a greenhouse farm would serve as the best place to collect rainwater. Gutter-connected greenhouses are gaining popularity, and growers are taking advantage of different filtration layers.

Below are the essential steps that you need to follow while using rainwater for greenhouse farming.


The quality of rainwater is outstanding, as it is in its purest form. Most rainwater is clean, but when it comes into contact with the roof and gutters, it may become polluted. Debris may get into the system, which you can easily filter through a filtration system.


Gutter-connected greenhouses collect the majority of rainwater that falls on their roofs. The gutters are connected to the downspout and piping system. The pipes take the rainwater into pre-constructed storage tanks or underground reserves.


Before entering the drip irrigation system, the pollutants and debris should be removed from the rainwater. The initial step while collecting and filtering the rainwater is to flush the first few liters of it. A small tank can also be used for this purpose. The flushed-out water can also be used for washing different farming equipment.


This is the last stage regarding the storage of rainwater for greenhouse farming. In most cases, a concrete cistern serves as a low-cost storage compartment. Moreover, it can also be a concrete septic tank. The largest septic tanks that you can buy offers a capacity of 5,000 gallons.



With the passage of time, clean water supplies are becoming scarce and hard to find. In this situation, trapping rainwater is the best and most feasible way to meet our freshwater needs.

Apart from using rainwater for domestic purposes, this kind of water source is serving as a viable option for farming. For instance, gutter-connected greenhouses are also using rainwater for drip irrigation.

Therefore, it is essential to learn about the process of trapping rainwater and making the most of it. The major steps of rainwater harvesting include collection, filtration, and storage. By using the latest technology, you can take more benefits by trapping the rainwater.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2020 Ben Martin

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