Introduction and Expansion of the Middle Water System (Fukuoka City, Tokyo): March 1995

Introduction and Expansion of the Middle Water System (Fukuoka City, Tokyo): March 1995

Background
The middle water system is a water supply system located between the water supply system and the sewage system, and it reuses purified water. It is mainly used for toilet flushing water and irrigation of plants. Especially in Western Japan, where water scarcity problems have become severe, the middle water system has attracted much attention.

Fukuoka City's Initiative
Fukuoka City was the first in Japan to introduce a full-scale middle water system. The "Sewage Treatment Water Circulation Utilization Model Project" started in 1979, and the supply to government buildings in the Tenjin area began in 1980. This system reuses treated sewage water and has been successful in the Tenjin area, the central business district of Fukuoka City. Currently, it supplies water to large facilities such as Fukuoka Dome and Fukuoka Tower, and recycled water is used for various purposes, including toilet flushing and park irrigation.

Tokyo's Case
Tokyo is also actively introducing the middle water system. A model project started in the Nishi-Shinjuku area in 1984, and currently, 19 office buildings are using recycled water. Recycled water is about 40% cheaper than tap water, contributing significantly to annual water bill savings. Additionally, the system is being laid in redevelopment areas, and the supply capacity is planned to expand to 8,000 cubic meters per day.

Expansion of Recycled Water Use
The introduction of the middle water system is spreading nationwide. According to the National Land Agency, in 1990, 1,369 cases of recycled water use were confirmed nationwide, accounting for 0.6% of the total domestic water use. Particularly, individual circulation systems are predominant, accounting for 60% of the total, but wide-area circulation systems from residential complexes and sewage treatment plants are also increasing.

Economic and Environmental Effects
The middle water system not only reduces water bills but also promotes sustainable use of water resources. In Fukuoka City's case, using recycled water has resulted in about a 40% annual cost reduction. Furthermore, the quality of recycled water meets tap water standards, ensuring safety.

Conclusion
The middle water system is an important technology for not only water scarcity measures but also environmental conservation and achieving a sustainable society. With the success stories of cities like Fukuoka and Tokyo as references, the introduction of this technology is expected to expand to more regions in the future. This technology provides significant economic benefits and environmental protection, playing an important role in promoting sustainable use of water resources.