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Best Ways on How to Filter Rainwater for Drinking

By June 4, 2018November 29th, 2020No Comments

The harvest of rainwater for domestic purposes has 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 dry season.

Due to population growth, global warming, and climate change, water has become scarce in many countries around the world. 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 various chemical wastes into huge bodies of water which leads to pollution. This phenomenon has become a global problem and government spends billions to address it immediately and sustainably. The supply of clean water has depleted, thus, an alternative method is harvesting of the 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 the 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 on how to filter rainwater to make it safe for drinking.

Brief Summary of Harvesting Rainwater

Although the Earth is covered with three-fourths part of water, only a little part of it is suitable for agriculture or human consumption.

Harvesting of rainwater started many years ago from the third century BCE in the farming communities of 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 which is based on man-made insulated collection wells.

Water is filtered down on the specially designed stone flooring, layers of sand, and it is collected at the bottom of the well. As years passed by, Venice has conquered territories on the mainland until it started importing clean water by the 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 got people conscious of their water supply and they started innovating ways to save water. They recycle water that can be used for several of tasks inside the home. Some of the structures built are the aqueducts, reservoirs, tanks, and pipes.

Benefits of Rainwater Harvesting

There are multiple benefits of collecting rainwater. Here are some of it:

  1. Solve the scarcity of water Rainwater harvesting can be one of the permanent solutions of the water crisis in various countries around the world. 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, the harvest of rainwater can be beneficial.

  2. Grow plants and tend the animals- A bad monsoon can lead to low crop produce and a shortage of food. Animals can suffer badly from lack of water too. For example, the Indian and African subcontinent are often faced with water crisis especially during summer season. 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.

  3. 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 an access to a water source are at high risk of contamination. This is also the case of Honduras, according to the UN-Habitat.

  4. 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, the level of groundwater 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 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 be able 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 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 of 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 survey and evaluation 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:

  1. 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 water which farmers can use for feeding the animals, farming, and other domestic purposes.

  1. 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. Thereafter, the water will reach a tank or a bucket using the plastic/ PVC pipes or bamboo/ wood pipes.

The first flow of the rainwater carries with it 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 the rain that your location receives. Meanwhile, you need to fill the pits with gravels, boulders, and sand that will filter the impurities that are carried with the rain’s first flow.

  1. Rainwater harvesting through solar panels

Both the solar energy and the rainwater are a renewable resource here on the Earth. Solar panels can also be used to harvest rainwater and convert it into drinking quality which is free from bacteria and any suspended matter. With the solar panels, it can power simple filtration and disinfection process among the rainwater.

Ways to Filter Rainwater

  1. 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 cell walls of the organisms and prevent its 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 effective, the right dose for a specific unit of water must be used. Here are some of the tips that you should try in using UV light in disinfecting rainwater:

  • Make sure to replace the UV light bulb after 12 months or 9,000 hours whichever comes first

  • 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 that are present in the rainwater collected. It must contain particulates that are no more than 50 microns and does 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 product about 10 gallons of clean water each minute.

  1. Filters and Disinfection

The effectivity of the filters can be measured via microns and the smallest size of 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 as the cartridge filters. They need to be changed regularly to prevent microorganisms to strive in the dirty environment.

Meanwhile, for rainwater systems requires 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 a quality drinking water. Some of the disinfection processes are UV light, chlorination, ozonization, and membrane filtration.

  1. Chlorine

Chlorine has been used for many years as a disinfectant for many public water systems in the schools or communities.

With chlorine, it has eliminated several water-borne diseases like hepatitis, dysentery, cholera, and typhoid and it has also saved the lives of thousands of people. However, chlorine has also side effects that’s why many people are hesitant with its use.

For one, chlorine is very reactive and it can easily combine with naturally occurring organic material that creates harmful chemical 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 still use chlorine but would like to reduce its harm, you can do the following:

  • Remove the by-products of chlorine by employing another purification process such as reverse osmosis.

  • 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.

  1. 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. You need to 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 time consuming and laborious, doing such method is beneficial to produce clean drinking water harvested from the rain.


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 longer period of time. However, you need to process it so it can be converted to safe and clean water that you can use inside your house, farm, and to tend your animals.

There are various methods of harvesting water which people has been using for many years. Apart from these methods, there are also several ways on how to filter rainwater so you can drink it. One of which is through the use of the Berkey Water Filters that you can buy here on our website. is a replacement water and air filter company located in the United States. The views and opinions contained herein are solely those of the original author and do not represent Eco Blue Life or its affiliates. This article was originally published on  
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