Published on the 12th of September, 2024
TOKYO’S EVER EVOLVING WATER LANDSCAPES
A THOUSAND YEARS
THE WATER FLOWS
– Japanese proverb
I was fortunate enough to visit Tokyo during the Mongolian Naadam holiday in July 2024—a perfect time to explore one of the world’s most fascinating megacities. The contrast between the festive celebrations back home and the sleek, fast-paced rhythm of Tokyo was striking. The very first impression of Tokyo, beyond the usual water utility stories, is how deeply the city embraces its traditions while simultaneously pushing the boundaries of technology and science. And this has also been reflected in its Urban Water Management.
Tokyo, with a population of about 14 million, is the beating heart of Japan’s economy, contributing a significant chunk to the country’s impressive GDP of over $5 trillion. Known for its hyper-modern infrastructure and urban planning, Tokyo’s achievements in water management and sanitation are just as noteworthy. The city has nearly universal access to clean drinking water and sanitation (A small percentage still remains in the mountainous areas, where their needs are met through on-site solutions).
Even though Japan is an island nation with limited natural water resources, Tokyo’s water supply is managed with impressive foresight. Around 80% of the city’s water comes from surface water sources, including rivers (Tone, Arakawa and Tama River) and reservoirs, with the rest sourced from groundwater. The Tokyo Waterworks Bureau operates an extensive network that supplies over 4 billion liters of clean water to its residents every day.
Tokyo’s rich history offers countless stories, but with only a few days to explore, I’ll focus on a select few topics. These are drawn from casual conversations with local experts, Takayuki Sawai and Takahiko Sakai (NJS Co., Ltd.’s Corporate Planning & PR Division). I want to take a moment to thank you both for the delightful conversation during one of the most unforgettable culinary experiences of my life (it was the Bonito, not the spanish Bonita :D).
I’ll focus on a few key topics:
Engineering solutions for the city’s utilities, including earthquake resilience, flood management, and tackling non-revenue water
The city’s highly effective community engagement systems in managing water resources
Current and future challenges like unsold water
Engineering solutions for the city’s utilities.
The very first water started to be supplied trough iron pipe UNDER PRESSURE (!!!) in 1898 and the Tokyo Waterworks were responsible for it. At the beginning all the pipes were imported from the foreign countries however with extensive effort and dedication the Tokyo has started producing its first pipes and progressively developed new methods on producing large scale
Tokyo Waterworks initially sourced its water from the Tamagawa River, but as the city rapidly grew, water demand surged, prompting the construction of reservoirs like Murayama Kami (1924) and Ogouchi (1957). During Japan’s post-1955 economic boom, water demand rose further, leading the government to initiate multipurpose dam projects and the 1962 Basic Plan for Water Resources Development. By 1967, Tokyo secured water from the Tonegawa via the Yagisama Dam and Musashi Canal. The government also developed the Arakawa River System as a water source in 1974, addressing both water needs and local relocation issues with the 1973 Water Resources Act*.
None Revenue Water and Management.
Like many major cities, Tokyo was losing 15 to 20 percent of its potable water to leaks—until 1980, when the water utility launched a new strategy. This plan focused on three key areas: deploying advanced technology to prevent leaks, early detection and repair, and systematically replacing aging mains and service pipes with durable materials, specifically stainless steel 316. With a sprawling network of 27,000 km, the challenge of pipe replacement was immense, but the potential savings were significant. After careful evaluation, the Tokyo Water Board decided to use stainless steel for service pipes and ductile iron for larger mains as part of a 30-year replacement program. Since most leaks occurred at pipe joints, engineers introduced flexible stainless steel pipes with intermittent corrugated sections to eliminate elbow joints.
By 2013, Tokyo Waterworks had reduced leakage from 15.4% to 2.2%, despite a growing and more water-demanding population, easing the strain on natural resources. The switch to more durable pipes also drastically cut maintenance cases from 69,000 in 1980 to just 10,000 in 2013. In addition, Tokyo Waterworks enhanced its leak management with early detection (by helium)* and repair methods, dividing the network into smaller blocks that are surveyed every decade. A 24/7 leakage team responds immediately to any visible signs of leaks, and the utility employs innovative techniques like helium inspections to detect hidden issues.
Earthquakes and the Pipe Networks.
Tokyo’s water pipe network has faced significant challenges due to its vulnerability to earthquakes, with several historic seismic events testing the city’s resilience. The most notable event was the Great Kanto Earthquake in 1923, which caused widespread damage to the water infrastructure, leaving much of the city without water for weeks. Following this disaster, Tokyo Waterworks implemented major upgrades, including the reinforcement of pipelines and the construction of earthquake-resistant water facilities.
After the 1995 Kobe earthquake, Tokyo further strengthened its water network with seismic technology designed to withstand high-magnitude quakes. A key aspect of Tokyo’s water infrastructure is the use of flexible joints and earthquake-resistant pipes, which can bend and move with the ground during tremors, preventing ruptures. The city also invested in emergency water storage facilities and backup systems to ensure water supply even in the event of severe seismic activity.
What makes Tokyo’s water infrastructure particularly remarkable is its ability to endure high-magnitude earthquakes without significant damage, a testament to decades of foresight, engineering innovation, and ongoing investments in disaster preparedness.Additionally, Tokyo’s water utility has divided its extensive pipe network into smaller blocks, making it easier to monitor and isolate damage in the event of a quake. This, combined with strategically placed emergency shut-off valves and backup systems, helps to quickly respond to and contain any leaks or breaks caused by seismic event. The replacement is ongoing (27,000km of pipework) trough prioritization of the facilities and areas. Read more here: https://www.waterworks.metro.tokyo.lg.jp/files/items/30209/File/3-2.pdf.
Tokyo Flooding and Prevention.
Flooding is a significant challenge for Tokyo, given its location and dense urban landscape, but the city has implemented impressive measures to manage and mitigate flood risks. Tokyo’s flood control strategy is a blend of advanced engineering, careful urban planning, and cutting-edge technology.
One of the standout features of Tokyo’s flood defense is the Metropolitan Area Outer Underground Discharge Channel, often referred to as the “underground shrine.” This massive underground facility, located in the outskirts of the city, consists of giant concrete silos and an extensive tunnel system designed to divert excess floodwater from rivers and storm drains. During heavy rains or typhoons, this system helps prevent urban areas from being overwhelmed, directing water away from populated districts and into the nearby rivers.During my travel I was lucky enough to be accompanied by my fellow colleague from Onewater INGO Risa san. Risa is a Former Marine Surveyor and a Pro Level English to Japanese translator. Shout out to her linkedin here: https://www.linkedin.com/in/risay-746119165/. Apart from her much needed guide to the location I thoroughly enjoyed her sense of humor and delightful light-hearted conversation.
The Metropolitan Area Outer Underground Discharge Channel, often called the “underground shrine,” is a massive flood control system located 50 meters beneath Saitama, near Tokyo. The facility stretches for approximately 6.3 kilometers (about 4 miles) and sits 50 meters (164 feet) below ground. The central feature is an enormous tunnel, 10 meters in diameter, designed to carry floodwaters away from urban areas to nearby rivers like the Edogawa River. Five colossal vertical shafts, each 70 meters high and 30 meters in diameter, act as storage silos to temporarily hold excess water. These shafts are connected by the main tunnel and serve to collect water from overflowing rivers and storm drains. The facility is equipped with four powerful turbines, each capable of pumping 200 tons of water per second, ensuring that water can be swiftly discharged into the rivers, reducing the risk of flooding in populated areas. At the heart of the system is a massive pressure-controlled water tank, also known as the “underground temple” due to its striking design with 59 pillars, each 18 meters tall. This chamber allows for controlled water flow and pressure management before water is pumped into the river. Designed to handle up to 50mm of rainfall per hour, this facility can manage enormous volumes of water, protecting Tokyo’s 13 million residents from devastating floods. The Metropolitan Area Outer Underground Discharge Channel took approximately 13 years to construct, with work starting in 1992 and completing in 2006. The total cost of the project was around ¥230 billion (about $2 billion USD*).
Community Engagement.
Tokyo’s highly effective community engagement systems in managing water resources are a key factor in the city’s successful water management strategy. The Tokyo Waterworks Bureau actively involves citizens in water conservation efforts, ensuring that the public is well-informed and engaged in safeguarding this vital resource. One of their most impactful initiatives is widespread public education on water-saving practices, from reducing household water consumption to using water-efficient appliances.
The bureau also encourages active participation through various campaigns and workshops, where citizens can learn about water usage, conservation techniques, and the importance of maintaining sustainable water practices. Examples are:
“Water Conservation Leader” Program: Tokyo Waterworks Bureau trains citizens to become “Water Conservation Leaders,” equipping them with knowledge about water-saving techniques. These leaders then engage their communities, schools, and workplaces to spread awareness about efficient water use. This grassroots approach ensures that water conservation becomes a community-driven initiative, with individuals serving as role models and educators in their local areas.
Water-Saving Appliances Subsidy: The city offers subsidies to residents and businesses that install water-saving devices, such as low-flow faucets and toilets. By directly incentivizing conservation at the individual level, this initiative encourages more sustainable water use practices while creating a personal financial benefit for participants.
Public Participation in Infrastructure Planning: Tokyo holds public forums and workshops where citizens are invited to learn about upcoming water infrastructure projects and provide feedback. These events create a transparent dialogue between the water authorities and the public, fostering a sense of ownership and trust in the system.
Real-Time Water Monitoring and Reporting App: Tokyo Waterworks provides an app that allows citizens to monitor their household water usage in real time, as well as report leaks and other water-related issues. This not only empowers individuals to track their consumption but also enables them to contribute to the city’s water management efforts by promptly reporting problems.
Another thing one must do is visiting the Tokyo Water Works Historical Museum which I have unfortunately skipped this time. The website is here:https://www.suidorekishi.jp/. Some maps of pipeworks from Edo period: https://www.ro-da.jp/suidorekishida/content/detail/K0077. AMAJING!!!
The Paradox of Water Management in Tokyo
Interestingly, during our visit, we learned about a unique challenge facing the Tokyo water authority. In recent years, the city has experienced a notable reduction in water consumption, largely due to the success of its conservation campaigns. While this is undoubtedly a positive development for environmental sustainability, it has unexpectedly caused financial difficulties for the water authority. With a significant drop in water sales, the revenue required to maintain and operate Tokyo’s vast water infrastructure has sharply declined. This shortfall has forced the authority to put a pause on its water-saving campaigns, as they now face the challenge of striking a balance between promoting conservation and ensuring financial stability.
And I have spent a handful of time and wine on how shall we move forward with such issues.
Future solutions could include adopting a tiered pricing system, where basic water use remains affordable, but higher consumption is charged at a premium. Diversifying revenue streams is also key—exploring options like selling excess water to neighboring regions, investing in water recycling technologies, or charging for additional services related to water management. But at what cost?
I will leave this to the readers and I am open for discussion. Please free to reach out to my LinkedIn or email.
To sum up, Tokyo is a remarkable example of urban water management, showing how hard work and determination can overcome big challenges. The city’s efforts have led to innovative solutions and advanced technologies that are now recognized worldwide. This case study shows that investing heavily in infrastructure not only solves current issues but also saves money in the long run for the benefit of everyone. It’s a great reminder that smart investments in water systems can bring lasting positive impacts for both people and the environment..