The harvest of rainwater for domestic purposes started a long time ago. People store rainwater so they can use something 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, becoming a serious concern for the government because it leads to illnesses and even deaths among citizens.
Modern homes and big companies nowadays dispose of various chemical wastes into huge bodies of water, which leads to pollution.
This phenomenon has become a global problem, and the government is spending billions to address it 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 friendly, rainwater harvesting is becoming popular.
It also leads to eco-conservation and 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 sustainable.
Thus, this article will discuss the history of harvesting rainwater, its benefits, and ways to harvest 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 agriculture 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 conquered territories on the mainland until it started 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 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 it:
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Solve water scarcity—Rainwater harvesting can permanently solve the water crisis in various countries worldwide. It is a workable solution for areas with sufficient rain but insufficient groundwater supply, such as hilly areas used by animals and humans. Rainwater harvesting can also be beneficial in remote areas where surface pollution is not problematic.
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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 do not have sufficient water to tend 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 water-borne diseases—Some communities worldwide lack clean water sources, so people must consume polluted water. As such, they are prone to water-borne diseases, which increase the mortality rate. According to studies, around 2 million people in Peru do not have access to any water supply, and those with access to a water source are at 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 will enable people to store it for future use, revitalizing the groundwater level and improving its quality. As such, groundwater levels will rise and become 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 demand for daily water consumption 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 needed to make the project sustainable 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 of the methods of harvesting water is surface runoff harvesting, which is best for urban areas.
In this kind of system, the rain, streams, and small creeks are redirected as surface runoff, and people can store it for future purposes.
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 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 the Earth. Solar panels can also harvest rainwater and convert it into drinking quality 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 the rainwater is through ultraviolet (UV) light. This method has been used for almost a century in Europe and has become popular in the United States.
The water first passes through a UV light-based filtration system. If the water doesn’t pass through the filters, the pathogens cast shadows in the flowing water, enabling the live organisms to pass unharmed.
UV light penetrates organisms' cell walls and prevents reproduction, making it harmless. It also does not change the water’s chemical composition or leave any by-products on it.
The right dose for a specific water unit must be used for UV light effects. Here are some of the tips that you should try when using UV light to disinfect rainwater:
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Make sure to replace the UV light bulb after 12 months or 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 might not be working. So, always check your tool and clean the glass enclosure so that the light will be effective. The UV treatment is correct and can reduce the harmful pathogens in the collected rainwater. It must contain no more than 50 microns particulates and do 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, and they can filter the smallest particle 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, ozonization, and membrane filtration.
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Chlorine
Chlorine has been used for years as a disinfectant for many public water systems in schools or communities.
Chlorine has eliminated several water-borne diseases like hepatitis, dysentery, cholera, and typhoid, and it has also saved thousands of people. However, chlorine also has side effects, so many people are hesitant about its use.
For one, chlorine is very reactive and can easily combine with naturally occurring organic material, creating harmful chemicals like 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 by-products of chlorine by employing another 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 Ziploc bag with rainwater, place the bag on two feet of aluminum foil, and place the shiny part in a sunny place in your home. Let the bag stay heated under the sun for several hours and remain at 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 to producing clean drinking water harvested from the rain.
For many years, people have been using various methods of harvesting water, one of which is Berkey Water Filters.
Conclusion
In summary, rainwater is free and not paid for. It is a renewable, long-lasting source of water.
However, it would be best to process it to convert it to safe, clean water that you can use in your house, farm, or animals.
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