Wednesday, November 3, 2010

Five Asian Success Stories - 3

“Water Conservation Conscious City” Program: Fukuoka, Japan

The city of Fukuoka suffers from a lack of fresh water with which to meet the demands of its 1.3 million citizens. The coastal city has experienced two major water shortages in the last 40 years; a drought in 1978 necessitated water restrictions for 287 days, seriously disrupting the local economy and the lives of residents.
In 1979 Fukuoka established a comprehensive plan for water conservation and usage. Fukuoka implemented an on-going leak detection program that discovers on average 800 leaks annually. The city also created an innovative water regulation system to control pressure and flow in distribution pipes. City engineers conduct night time surveys of 2900 km. (1802 miles) of water distribution pipe one city block at a time using electromagnetic flow meters on a four-year cycle. Areas at high risk of leaking and those areas where leaks could create accidents are monitored on a more regular basis. Faulty pipes and older pipes – typically made from unlined iron – are replaced with ductile iron pipes lined with cement mortar or fusion bonded epoxy which reduces the risk of leakage. A system of pressure gauges, flow meters, and motor valves have been installed throughout the city that monitor and regulate water pressure and flow on a 24- hour basis, again reducing the potential for leakage.

The results have been significant. A study carried out in 2000 found that Fukuoka consumes 20% less water than other Japanese cities of a comparable size. Reductions in water leakage have increased effective supply to 96.5% of the distributed amount, the highest figure of a major Japanese city. Distribution regulation systems save approximately 5 million liters (1.32 million gallons) per day and have reduced the incidences of naturally occurring leakages by 30%.

The water conservation program included a public education campaign which resulted in 94% of users having water flow reducing devices installed in their homes which produced savings of approximately 1,000 liters (264 gallons) per month per home (for a family of four).

The city also built a three-part collection and distribution system for the reuse of grey water for non-drinking purposes. One part of the system redistributes reclaimed water to 7.7 square kilometers (3 square miles) in the central part of the city (which includes the City Hall and subway stations). Another part provides reclaimed water to several apartment complexes which have their own treatment facilities that re-circulate reclaimed water within the complexes. The third part provides reclaimed water to any large new buildings within the city. Total savings are approximately 7 million liters (1.85 million gallons) of potable water each day.

Wastewater reclamation has the greatest potential in urbanized areas as the costs associated with building a separate distribution system are high. Even though it is sold to consumers for less than potable water, and in spite of the high capital costs associated with building a residential grey water re-distribution system in a high density area, Fukuoka recoups a small margin on the sale of reclaimed water- approximately US$1/M3. The Fukuoka example indicates that the reuse of water for residential toilet flushing and urban irrigation (parks, golf courses) can be economically and environmentally justified, especially in water scarce areas.

Goal: To increase the cities water security by reducing the volume of water lost through distribution channel leakage and by raising water conservation awareness among the public.
Length of Project: Leak prevention program was initiated in 1956; Leakage detection and pipe replacement programs started in 1965; concentrated leak surveying in high incidence areas began in 1972; Water distribution control technology introduced in 1981
Funders: City of Fukuoka
Public Works Research Institute of Fukuoka
1-6, Minamihara
Tsukuba-shi, Ibaraki-ken
305-8516 Japan
Phone: +81-29-879-6700

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