When you turn on a tap, have you ever wondered what proportion of water leaks out of the pipes it must travel through to get from the waterworks facility to the tap you have just opened? This proportion is called the “leakage rate,” and looking at waterworks facilities around the world, those with high leakage rates record losses of between 30–40% before the water reaches the tap. Even in large cities with an advanced waterworks system, the average leakage rate is around 10%. Leaking water is an everyday occurrence in almost all of the water pipes across the entire world.
In Tokyo, however, the leakage rate is tiny at just 3.6%.
This figure was first made public at the second Large Cities Climate Change Summit, in 2007, and its low level shocked the summit delegates, gathered from around the world.
By this 3.6% leakage rate, Tokyo prevented water leakage equivalent to the same amount of water as that used in a year by a city of 3.5 million that has the avarage leakage rate; this comparison should indicate how important such figures are. Japanese cities other than Tokyo also have a low leakage rate. Even those with higher rates generally maintain ratios of less than 10%, and the national average is around 7%. These figures are dropping on an annual basis (In 2010, the leakage ratio for Tokyo was 3.1%).
For regions that are lacking in water resources, being able to secure even just a little more water for domestic use can be a question of life and death; instability in water supply is an extremely series issue. The outstanding waterworks system technology that Japan has developed can greatly benefit society in such countries.
Well-designed sewage systems are also an extremely important technology in terms of recycling and reusing our precious water resources. Here, we introduce Japan’s waterworks and sewage systems.
The Waterworks of the Great City of Edo: Working Toward a Steady Water Supply
Japan has one of the most outstanding water and sewage works of any country in the world. Japanese people have long been aware of the importance of maintaining water supply facilities. Water facilities have supported urban populations ever since the castle town of Edo (now Tokyo) was built in the Middle Ages; supply lines providing clean water for domestic use have been continuously developed and improved.
From the second half of the 16th century through to the 17th century, Edo was built as a new city for a new generation of political administrators. During its peak years, the population of Edo reached 1 million residents.
In comparison, 17th century London and Paris both had populations of around half a million, which is a clear indication of just how massive Edo was at the time. The first water supply system was built in 1590, in order to provide water for the domestic use of this enormous population; eventually, a total of 152 km of underground waterways had been constructed. These waterways supported around 60% of Edo’s population.
The water supplied through these waterways was of extremely high quality. The water facilities of Edo were highly advanced for their time, extremely rare on even a global scale.
In the 19th century, Japan opened the borders it had previously closed off to the outside world, and began to establish active relations with foreign countries. One of the results was that Western waterworks technology was introduced into Japan, including modernized filtration treatments.
By that time, Japan already had over 500 years of accumulated knowledge and know-how on waterworks technology, and with the introduction of modernized technology once again aimed to establish the world’s most advanced waterworks systems.
Japan’s outstanding waterworks system is supported by multiple factors: the material used for the water pipelines, excellent joint technology, acoustic technology that allows technicians to located leaks from above the ground, pipework adjustment and management, the management structure in place for controlling water pressure, as well as the technical skills of experts with many years of knowledge in the field.
The high leakage rate records for water pipelines in many countries is a result of the age of those pipes, as well as a lack of adequate management and a low level of relevant technology. A high level of leaking water is also related to decline in water quality. It is not possible to maintain high pressure within the water pipelines and at the leaking points along the pipe there is a heightened risk of pollutants entering the water.
Today, technicians from Japan’s local authorities and waterworks companies are dispatched to countries all over the world, where they work to improve the management of waterworks facilities and the availability of clean water. Japan’s expertise and technology has contributed to the leakage rate in cities in developing countries falling from 40% to less than 10%.
Working Toward Advanced Water Recycling
Reclaimed water businesses have become very active in Japan in recent years. Reclaimed water refers to sewage water and rainwater that has been subject to advanced purifying treatment and can be reused.
It is not suitable for drinking water, but it can be used for toilets and fire preventing in urban areas. Today, reclaimed water services are being actively operated in large cities such as Tokyo.
This reclaimed water has attracted significant global attention. Supplying reclaimed water to those places where supplied water is not required to be at the level of drinking water quality represents an effective solution in dealing with increasing water demand as well as water shortage issues.
This reclaimed water is a result of Japan’s advanced sewage processing technology. Filtering technology required to process polluted water and desalinate sea water has reached an extremely high level of advancement in Japan, and it is this kind of technology that has made reclaimed water services possible.
Filtration membranes manufactured in Japan account for a significant share of all such membranes used throughout the world. In addition, Japanese sewage treatment technology, sea water desalination technology, and reclaimed water services are rightly the subject of great interest from overseas.
The world’s population continues to grow unchecked and industry advances with it. There is no apparent end in sight to the rapid increase in water demand experienced in recent years.
The questions of how to most efficiently transport water from its source to the location of human activity, and how to most effectively reclaim and recycle water in order to maximize limited water resources, as well as how to secure safe, clean water for all are vitally important. Japanese technology certainly has much to contribute in finding the solutions to these challenges.
March 8, 2012
About the author
Hiromi Jitsukata is a reporter for Japanest NIPPON
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