Epidemic of cholera
In Osaka, there was an epidemic of cholera in 1886 and the breakout of a big fire in 1890. With these two disasters as a trigger, Osaka introduced its public water service about 120 years ago in response to the growing need for easier access to sanitary water and for disaster prevention, especially fire mitigation.
Water Supply System construction
The Osaka City Waterworks Bureau was born in November 1985 as the fourth largest modern waterworks following facilities at Yokohama, Hakodate, and Nagasaki. The water supply population at the time was 610 thousand, with a maximum water supply capacity of 51,240㎥/day. The water purification plant was located at Sakuranomiya on the left bank of the Yodo River and this plant transmitted water purified by slow filtration to a water distribution reservoir in Osaka Castle, from where it was supplied to Osaka City by natural down-flow through a water distribution pipes totaling 325 km in length. Total operational budget was 2.4 million yen（three times the city budget at the time）
The first Water Purification Plant in Osaka City
Subsequently, as the city developed, a growing water demand made it impossible for the Sakuranomiya water resource to satisfy needs and this resulted in the implementation of an expansion of operation nine times including the construction of the Kunijima Water Purification Plant in 1914 during second waterworks expansion project.
Serious water pollution
In 1960s, serious water quality deterioration was caused by solid waste dumping and direct discharge of industrial wastewater.
Sewerage system construction
Sewerage construction in Osaka city began about 120 years ago and was the first large scale modern sewerage system at that time. Since then, the Osaka city government has led at the top level in terms of sewerage system coverage among major cities in Japan.
Recently, an advanced treatment system has been widely applied and the treated water has been reused in various applications in an effort to contribute to restoring the urban environment.
The first sewerage treatment plant in Osaka city
In 1925, a pilot sewerage treatment plant was constructed in Osaka city and, based on the results, a sewerage development plan was formulated. The construction of Tsumori Sewerage Treatment Plant, the first sewerage treatment plant in Osaka city, began in 1931 and was completed in 1940. It made it possible to treat sewerage instead of discharging it to rivers directly.
Environmental water enhancement
Osaka Castle moat
A large volume of treated water from sewerage treatment plants can also become a new resource in the urban water environment. By flowing advanced treated water into rivers that had lost their water resources due to urbanization, a beautiful waterfront environment with the natural sounds of a babbling brook (seseragi) can be restored in urban areas. The same process serves to restore the water level of the moat of Osaka castle.
Serious air pollution
Since the 1960s, factories and cars have increased and, sometimes, because of the smog, people had to drive their cars with headlights on even during daytime hours. However, air quality has been recovered dramatically by the diligent efforts that included various approaches.
Incineration plants in Osaka city
The first incineration plant in Osaka city was constructed in 1903.
Solid waste treatment was done by manpower at that time
In the 1960s, construction of incineration plants with mechanical furnaces started and the work in the plants was mechanized.
At present, not only is waste incineration done hygienically and effectively by using advanced incinerators that are operated automatically, but also the heat from the waste incineration process is reused for power generation.