How Rainwater is Harvested and Used in Different Countries


How Rainwater is Harvested and Used in Different Countries


It's no wonder that rainwater harvesting, the accumulation and storage of rainwater for future use, is one of the most well-known proposed solutions to saving the world's supply of water from dwindling constantly to the point of depletion. After all, water gathered this way, provided that it is treated and filtered well, can be used for gardening, raising livestock, irrigation, washing dishes and clothes, bathing, and even drinking.


Aside from being a great alternative source of water (especially in areas that often experience water shortage), rainwater harvesting, provided that it is done by many, also helps prevent floods and soil erosion from happening in an area. This is because rainwater is redirected to tanks (or other means of storage) as soon as they fall from the sky to the roof (or ground).


Still, another advantage of the practice is its being able to help reduce the world's overall carbon footprint. Remember that getting water pumped over long distances requires a lot of power, which only fossil fuels, which are environmentally-harmful, can provide.


These advantages stated above are just some of the many reasons why people in many countries are practising it. Here are some examples of rainwater harvesting in different parts of the world.




In its capital, Tokyo, the practice of rainwater harvesting is promoted to control floods, secure water for emergency use, and solve water shortage somehow.


Sumida City's Ryogoku Kokugikan Sumo Wrestling Arena, which was built in 1985, is one of the city's most well-known facilities that use rainwater. The 8,400 square-meter rooftop of the arena serves as the catchment of its rainwater harvesting system. The rainwater collected is then drained to a large underground tank. It is then used to supply taps, toilets, and air conditioning units with water. The same city's city hall also makes use of a similar rainwater harvesting system. Following these examples, several public establishments have started introducing these systems elsewhere.


At the community level, a simple rainwater harvesting system called Rojison was set up to maximise the use of rainwater. The collected rainwater is used for gardening, as an alternative water resource during emergencies, and fire fighting.


To this day, more than 700 public and private buildings in Tokyo have this system set up. Nowadays, the harvesting and use of rainwater is flourishing at the private and public levels.




In 1998, systems for harvesting rainwater were introduced for urban re-development on a large scale, control floods, save water, and create a much better local climate. The rainwater that falls on the roofs of nineteen buildings is stored in a single basement tank. This is used to flush toilets, water plants in gardens, and replenish artificial ponds.


Another similar project saw the discharge and transfer of rainwater from roofs to a rainwater sewer, together with run-off from roads, pathways, and parking spaces. The water gathered is then treated in numerous stages before it is used for gardening and toilet flushing. The design of this system ensures that many pollutants are flushed out from the rainwater sewer to the sanitary sewer so it can be property treated in sewage plants. A lot of rainwater has been retained using such a system. Also, according to a simulation, thousands of cubic meters of potable water are saved each year, therefore preserving Berlin's groundwater reservoirs by almost the same amount.


These systems do not just conserve the city's water, they also decrease the chances of pollutant discharges from sewage heading into surface water. This approach to controlling any source of pollution is essential when it comes to protecting the quality of surface water in urbanised areas.




In this Southeast Asian country, groundwater is slowly becoming scarcer in urban areas because of low water infiltration. The decline of groundwater recharge in the country's major cities is proportional to an increase of water falling to the roofs and pavements of buildings. The constant increase of population has also caused groundwater to be consumed at high rates.


Recognising the necessity of having drainage systems altered, the country's government introduced a law requiring all buildings to have infiltration wells (a type of underground rainwater harvesting system). This law applies to much of the country's territory. In previous studies, it was said that if every home in Madura and Java had their own infiltration well, water deficit will go down by significant levels. This translates to a 16% net savings through conservation.




Most of the people of Thailand have long made use of big jars to store rainwater that falls from roofs. In the past, the jars they used did not have protection from mosquitoes and waste, but these days, they no longer face these issues as the jars they use have taps, drains, and lids. The jars come in capacities ranging from 100 to 3,000 litres.


There are two methods to make the use of these water jars more widespread and encouraged. The first involves training villages on how to make them. This approach has been great for several villages so far due to several reasons, one being that it encourages villagers to work together. In addition, this method serves as a good way of earning money, as it is easy to learn and only requires affordable materials.


The second approach to getting more water jars is best for those villages which don't have the manpower needed to create these water jars. A revolving loan fund is given to villagers so they can buy jars.


Along with these approaches, maintaining these jars and the right way of securing safe drinking water are taught. So far, the rainwater jar project has been successful, and has eventually encouraged the government of Thailand to make this a national program.




In this South Asian nation, the collection and storage of rainwater is considered as an option for safe drinking water, especially in areas affected by the spread of arsenic. Since the late 90s, more than a thousand rain harvesting systems have been set up in the nation by non-government organisations.


Rainwater storage tanks usually used in Bangladesh have a capacity of 500 to 3,200 litres and are made of various materials and structured differently. The water harvested and used in these tanks is useful for a wide range of purposes, including cooking and drinking. This is mainly due to the fact that the population is doing everything they can to make their water clean for five months. For this reason, the same non-government organisations that are promoting this practise to the local population are now endorsing the practice and its results to the government.


Despite the benefits offered by rainwater harvesting in these and in many other areas around the world, there still are places that do not practise it. Some reasons include their governments having other priorities or their governments banning the practice outright. With the global water crisis just around the corner, it probably is high time to reconsider encouraging this practice among cities and nations, and one way to help is by making your own system or discussing its benefits with those in power. Information on high-quality rainwater tanks and pumps you can use can be found here:

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