The harvest of rainwater for domestic purposes started a long time ago. People stores rainwater so they can use something to quench their thirst, clean their body, 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. Water levels have dropped gradually, and it has become a serious concern for the government because it leads to illnesses and even death of the 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 spends billions to address it immediately and sustainably. The supply of clean water has depleted. Thus, an alternative method is the harvesting of rainwater.
Harvesting rainwater is a simple and practical way to deal with the water crisis. As people become environment-friendly nowadays, 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 now falling, and many people have become dependent on bottled water which is costly and sustainable.
Thus, in this article, we will discuss the history of harvesting rainwater, its benefits, and ways to harvest rainwater. 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.
Harvesting of rainwater started many years ago from the third century BCE in Pakistan, Iran, and Afghanistan to be used for agriculture purposes and other domestic use. In ancient Indian communities, they collected rain and stored it in tanks for drinking and farming irrigation.
Also, the town of Venice depended on rainwater harvesting for centuries. The lagoon around Venice is brackish water which is not safe for drinking. As such, the ancient citizens of Venice established a system of collecting rainwater based on artificial insulated collection wells.
Water is filtered down on the specially designed stone flooring, layers of sand, and 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, they still use the wells, and it has become important during war times when access to the mainland is blocked by the enemy.
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 of the structures built are aqueducts, reservoirs, tanks, and pipes.
Benefits of Rainwater Harvesting
There are multiple benefits of collecting rainwater. Here are some of it:
- Solve the scarcity of water- Rainwater harvesting can be one of the permanent solutions to the water crisis in various countries worldwide. This is a workable solution for areas with sufficient rain but with insufficient groundwater supply. This is true in hilly areas, which are used for both animals and humans. Also, in remote areas where surface pollution is not problematic, rainwater harvest can be beneficial.
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Grow plants and tend the animals- A bad monsoon can lead to low crop production and food shortage. Animals can suffer badly from lack of water too. For example, the Indian and African subcontinent are often faced with water crises, especially during the summer. Farmers are greatly affected because they cannot 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- Since some of the communities around the world don’t have a clean water source, people don’t have a choice but to consume polluted water. As such, they are prone to water-borne diseases, and the mortality rate increases. According to studies, around 2 million people in Peru do not have access to any water supply, and those who have access to a water source are at high risk of contamination. This is also the case of Honduras, according to the UN-Habitat.
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Revitalize the groundwater level- Harvesting rainwater will enable people to store it for future use. With this, the groundwater level will be revitalized, and its quality will soon improve. As such, groundwater levels will rise, and it can become easily accessible in the future. Ground wells will be prevented from drying up, and it can also increase soil fertility. Finally, it can prevent surface runoff and reduce erosion of the soil.
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 a plumbing job, and the outlets on the building terrace are connected using a pipe in an underground tank which can store the water.
The size of a rain harvester must be big to meet the demand of daily water consumption throughout the dry season. The capturing area of the roof of the building must be wide to maintain the adequate flow of the water. Also, the water storage tank should be huge to store the captured water.
It will be useful to use several digital tools before building a rainwater harvester system. For example, if you wish to determine if your area has a high potential for rainwater, you can use the GIS map scanning, and this is an online interactive tool.
Meanwhile, if you wish to know how much water is needed to supply the needs of your community, you can also utilize the ‘Rain is Gain’ tool.
With this, you can save time, money, and effort before committing to a system. Also, proper surveys and evaluations are needed to make the project for your home or your community sustainable.
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 through the use of surface runoff harvesting, and this 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 can be used in reservoirs, tanks, and ponds. Also, surface runoff can give farmers water for feeding the animals, farming, and other domestic purposes.
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Rooftop rainwater harvesting
This type of rainwater harvesting can be done in schools, offices, and homes. People can do this by intercepting the rainwater to flow in a definite direction only. After that, the water will reach a tank or a bucket using plastic/ PVC pipes or bamboo/ wood pipes.
The first flow of the rainwater carries some leaves, dust, insects, and animal droppings. With that, it is best to use a detachable downpipe so you can divert the first flow of the rainwater.
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 need to fill the pits with gravels, boulders, and sand that will filter the impurities carried with 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 be used to harvest rainwater and convert it into drinking quality free from bacteria and any suspended matter. The solar panels can power a simple filtration and disinfection process among the rainwater.
Ways to Filter Rainwater
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Ultraviolet Light
One way to disinfect the rainwater is through the use of ultraviolet (UV) light. This method has been used for almost a century in Europe, and now it has become popular in the United States.
With the UV light method, the water will pass first in a filtration system. If the water didn’t pass through the filters, the pathogens will cast shadows in the flowing water and enable the live organisms to pass through unharmed.
The UV light works by penetrating the organisms' cell walls and preventing their reproduction, thereby making it harmless. Also, UV light does not change the water’s chemical composition, plus it does not leave any by-products on it.
To make the UV light effects, the right dose for a specific water unit must be used. Here are some of the tips that you should try in using UV light in disinfecting 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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The UV light is not visible to the naked eye. It may appear to be lit. However, it might not be working. So always check your tool and clean the glass enclosure so that the light will be effective.
If the UV treatment is correct, it can reduce the harmful pathogens present in the rainwater collected. It must contain particulates that are no more than 50 microns 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.
Typically, the UV light is installed after all the filtration systems, and it can thereby result in clean water, free of bugs, and ready to use. The UV light entry-level can produce about 10 gallons of clean water each minute.
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Filters and Disinfection
The effectivity of the filters can be measured via microns and the smallest size of the particle that they can filter. Indeed, the smaller the micron size, the better the filter is. However, it is costly, and the filtration process is smaller.
The first filter in a system is called the cartridge filter. They need to be changed regularly to prevent microorganisms from striving in a dirty environment.
Meanwhile, rainwater systems require a larger filter which is 50 microns or more, to be used to eliminate the sand, insects, pebbles, and other larger particles.
Aside from the filter, it will also require a disinfection process to create quality drinking water. Some of the disinfection processes are UV light, chlorination, ozonization, and membrane filtration.
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Chlorine
Chlorine has been used for many years as a disinfectant for many public water systems in schools or communities.
With chlorine, it 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; that’s why many people are hesitant about its use.
For one, chlorine is very reactive, and it can easily combine with naturally occurring organic material that creates harmful chemicals like chloroform.
To disinfect rainwater, you can have 2.3 fluid ounces of chlorine per 1,000 gallons of water. 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.
To remove the smell and the taste of chlorine in the drinking water, you can use an activated carbon filter or charcoal filter. This system is made of coconut shells, carbon, and other eco-friendly solution.
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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 the rainwater, place the bad on two feet of aluminum foil, and place the shiny part on a sunny place in your home. It would be best if you let the bag stay heated under the sun for several hours, and it should remain at about 160 degree-Fahrenheit or higher. With this, the water-borne bacteria can be eliminated in the water.
Although this method can be time-consuming and laborious, doing such a method is beneficial to produce clean drinking water harvested from the rain.
There are various methods of harvesting water that people have been using for many years. One of which is through the Berkey Water Filters.
Conclusion
In sum, rainwater is free, and you don’t have to pay for it. It is one of the renewable sources of water, and it can stay for a more extended period. However, it would be best if you processed it to be converted to safe and clean water that you can use inside your house, farm, and tend your animals.
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