The harvest of rainwater for domestic purposes started a long time ago. People store rainwater so they can use it to quench their thirst, clean their bodies, and feed their animals, especially during the dry season.
Due to population growth, global warming, and climate change, water has become scarce in many countries worldwide. Gradually, water levels have dropped, posing a serious concern for the government, as it leads to illnesses and even deaths among citizens.
Modern homes and large companies often dispose of various chemical wastes into large bodies of water, leading to pollution.
This phenomenon has become a global issue, and governments are spending billions to address it both immediately and sustainably. However, the supply of clean water has depleted. Thus, an alternative method is harvesting rainwater.
Harvesting rainwater is a simple and practical way to address the water crisis. As people become more environmentally conscious, rainwater harvesting is gaining popularity.
It also promotes eco-conservation and the smart use of natural resources. The water tables in most urban areas are falling, and many people have become dependent on bottled water, which is costly and unsustainable.
Thus, this article will discuss the history of harvesting rainwater, its benefits, and the methods for harvesting it. In the last part, we will also tackle the four methods of filtering rainwater to make it safe for drinking.
Brief Summary of Harvesting Rainwater
Although the Earth is covered with three-fourths of water, only a small part is suitable for agriculture or human consumption.
The harvesting of rainwater started many years ago, in the third century BCE, in Pakistan, Iran, and Afghanistan, and it was used for agricultural purposes and other domestic uses. In ancient Indian communities, they collected rain and stored it in tanks for drinking and farming irrigation.
For centuries, the town of Venice also depended on rainwater harvesting. The lagoon around Venice contains brackish water, which is unsafe for drinking.
As such, the ancient citizens of Venice established a system of collecting rainwater based on artificially insulated collection wells.
Water is filtered down through the specially designed stone flooring, and layers of sand are collected at the bottom of the well.
As the years passed, Venice expanded its territories on the mainland until it began importing clean water by boat from the local rivers.
However, Venice still used the wells, which became important during the war when the enemy blocked access to the mainland.
Today, climate change has made people conscious of their water supply, and they have started innovating ways to save water. They recycle water that can be used for several tasks inside the home. Some structures built are aqueducts, reservoirs, tanks, and pipes.
Benefits of Rainwater Harvesting
There are multiple benefits of collecting rainwater. Here are some of them:
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Solve water scarcity—Rainwater harvesting can permanently solve the water crisis in various countries worldwide. It is a viable solution for areas with sufficient rainfall but an insufficient groundwater supply, such as hilly regions used by both animals and humans. Rainwater harvesting can also be beneficial in remote areas where surface water pollution is not a significant issue.
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Grow plants and tend the animals—A bad monsoon can lead to low crop production and a food shortage. Animals can also suffer badly from a lack of water. For example, the Indian and African subcontinents often face water crises, especially during the summer. Farmers are greatly affected because they lack sufficient water to tend to their animals and plants. Thus, rainwater harvesting is the answer for farmers who rely on the monsoon for water supply.
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Prevent waterborne diseases—Some communities worldwide lack access to clean water sources, forcing people to consume contaminated water. As such, they are prone to water-borne diseases, which increase the mortality rate. According to studies, approximately 2 million people in Peru lack access to a water supply, and those with access to a water source are at a high risk of contamination. This is also the case in Honduras, according to UN-Habitat.
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Revitalize the groundwater level—Harvesting rainwater enables people to store it for future use, thereby revitalizing the groundwater level and improving its quality. As a result, groundwater levels will rise and become more easily accessible. Ground wells will be prevented from drying up, and soil fertility can also increase. Finally, it can prevent surface runoff and reduce soil erosion.
System Set-up
The system of harvesting rainwater can vary in complexity. It can be installed with no professional skill using simple parts, or you can have an automated system that requires advanced installation and tools.
Its basic system requires plumbing work. The outlets on the building terrace are connected to an underground water storage tank through a pipe.
A rain harvester must be large enough to meet the daily water demand throughout the dry season. The capturing area on the building's roof must be wide to maintain an adequate water flow. The water storage tank should also be huge.
Several digital tools will be useful before building a rainwater harvester system. For example, you can use GIS map scanning, an online interactive tool, to determine whether your area has a high potential for rainwater.
Meanwhile, the ‘Rain is Gain' tool can also help you determine how much water is needed to supply your community's needs.
Before committing to a system, this can save you time, money, and effort. Proper surveys and evaluations are also necessary to ensure the project's sustainability for your home or community.
Methods of Rainwater Harvesting
The most common methods for rainwater harvesting are the following:
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Surface runoff harvesting
One method of harvesting water is surface runoff harvesting, which is particularly suitable for urban areas.
In this type of system, rain, streams, and small creeks are redirected as surface runoff, allowing people to store it for future use.
This water can be used in reservoirs, tanks, and ponds. Surface runoff can also provide farmers with water for feeding animals, farming, and other domestic purposes.
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Rooftop rainwater harvesting
Rainwater harvesting can be done in schools, offices, and homes. People intercept rainwater so it flows only in a definite direction. Then, the water reaches a tank or a bucket using plastic, PVC, bamboo, or wood pipes.
The first flow of rainwater carries some leaves, dust, insects, and animal droppings. With that, it is best to use a detachable downpipe to divert the rainwater's first flow.
You can also construct recharge pits that can hold the rainwater. You can have it in any size or shape, depending on the amount of rain your location receives. Meanwhile, you must fill the pits with gravel, boulders, and sand to filter the impurities from the rain's first flow.
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Rainwater harvesting through solar panels
Both solar energy and rainwater are renewable resources here on Earth. Solar panels can also harvest rainwater and convert it into drinking-quality water free from bacteria and suspended matter. The solar panels can power a simple filtration and disinfection process in rainwater.
Ways to Filter Rainwater
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Ultraviolet Light
One way to disinfect rainwater is through the use of ultraviolet (UV) light. This method has been employed for nearly a century in Europe and has gained popularity in the United States.
UV light penetrates organisms' cell walls and prevents reproduction, making it harmless. It also does not alter the water’s chemical composition or leave any byproducts behind.
The correct dose for a specific water unit must be used to achieve UV light effects. Here are some of the tips that you should try when using UV light to disinfect rainwater:
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Replace the UV light bulb every 12 months or after 9,000 hours, whichever comes first.
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UV light is not visible to the naked eye. Although it may appear to be lit, it may not be functioning properly. Therefore, always check your tool and clean the glass enclosure to ensure the light is adequate. It must contain no more than 50 microns of particulates and must not contain sulfur, tannins, or sulfur-related bacteria. It must also have 0.005 parts per million less manganese and less than 0.3 parts per million of iron.
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Typically, the UV light is installed after all the filtration systems, resulting in clean, bug-free water ready to use. The entry-level UV light can produce about 10 gallons of clean water each minute.
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Filters and Disinfection
The effectiveness of the filters can be measured in microns, allowing them to filter particles of the smallest size. Indeed, the smaller the micron size, the better the filter. However, it is costly, and the filtration process is slower.
The cartridge filter is the first filter in a system. It must be changed regularly to prevent microorganisms from flourishing in a dirty environment.
Meanwhile, rainwater systems require a larger filter of 50 microns or more to eliminate the sand, insects, pebbles, and other larger particles.
A disinfection process will be required in addition to the filter to create quality drinking water. Disinfection processes include UV light, chlorination, ozonation, and membrane filtration.
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Chlorine
Chlorine has been used for years as a disinfectant in many public water systems, including those in schools and communities.
Chlorination has eliminated several water-borne diseases, including hepatitis, dysentery, cholera, and typhoid, and has also saved thousands of people. However, chlorine also has side effects, so many people are hesitant about its use.
For one, chlorine is highly reactive and can easily combine with naturally occurring organic matter, creating harmful chemicals such as chloroform.
You can have 2.3 fluid ounces of chlorine per 1,000 gallons of water to disinfect rainwater. It also depends on the quantity of water, temperature, and pH level. Meanwhile, if you wish to use chlorine still but would like to reduce its harm, you can do the following:
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Remove the byproducts of chlorine by employing an additional purification process, such as reverse osmosis.
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Use filters to remove the particulates or organics in the water before treating it with chlorine.
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Activated carbon or charcoal filters can remove the smell and taste of chlorine from drinking water. This system uses coconut shells, carbon, and other eco-friendly solutions.
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Solar pasteurization
The last method of filtering rainwater is through solar pasteurization. This system is labor-intensive, unlike all other methods.
To do this, fill a Ziplock bag with rainwater, place the bag on two feet of aluminum foil, and position the shiny side in a sunny spot in your home. Let the bag stay heated in the sun for several hours, maintaining a temperature of about 160 degrees Fahrenheit or higher. With this, water-borne bacteria can be eliminated from the water.
Although this method can be time-consuming and laborious, it is beneficial for producing clean drinking water harvested from the rain.
For many years, people have been using various methods to harvest water, one of which is the Berkey Water Filter.
Conclusion
In summary, rainwater is free and not subject to payment. It is a renewable, long-lasting source of water.
However, it would be best to process it to convert it into safe, clean water that you can use in your home, on your farm, or for your animals.
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