The Era of Domestic Wastewater - The Turbulence of Life in Tokyo Bay in the Early 1990s

The Era of Domestic Wastewater - The Turbulence of Life in Tokyo Bay in the Early 1990s
In the early 1990s, the focus of Japan's environmental problems was shifting from "factories" to "homes." While the four major pollution lawsuits of the 1970s had ended and heavy metal and chemical pollution had decreased, it was wastewater from our daily lives that began to threaten the urban waterfront. Oil from the sink, detergent, soap from the bathtub, and wastewater from the washing machine all merged together and flowed into Tokyo Bay via rivers without being treated. The Environmental Agency (now the Ministry of the Environment) reported in 1994 that this untreated wastewater accounted for about 40% of the pollution in the bay.
At the time, Tokyo Bay appeared to be a calm inner bay, but inside it was seriously "eutrophied. The concentrations of phosphorus and nitrogen rose, and blue and red tides frequently occurred in the summer. The sight of fish and shellfish dying in large numbers was now commonplace in some areas. Although much of the wastewater came from households, the national average sewage system was only about 45%, and the spread of sewage systems was slow, especially in suburbs and small- and medium-sized cities. While housing development was progressing, wastewater treatment systems were not keeping pace, creating an ironic situation in which "clean living" was conversely leading to water pollution.
This problem emerged due to urban expansion and lifestyle changes during the bubble era: In the late 1980s, the number of private homes and condominiums increased rapidly in urban areas, and per capita water consumption increased dramatically due to the spread of home appliances and hot-water supply systems. The "comfort" of life led to increased water consumption, which in turn led to an increase in wastewater. In addition, household detergents and shampoos contain high levels of phosphates and surfactants, which are believed to have contributed to the eutrophication of Tokyo Bay.
On the other hand, this situation also highlighted the limitations of the government. The construction of sewage systems is extremely costly and time-consuming, making them unprofitable, especially in areas with low population density. As a result, "stand-alone septic tanks"-that is, systems that treat only toilet wastewater-remained the norm in rural areas, and kitchen and bath water was discharged untreated.
In response to this problem, the "combined treatment septic tank" was introduced in the mid-1990s. The government subsidized the installation of these tanks and promoted them in earnest with the amendment of the law in 1994. In the Kojima Lake basin in Okayama Prefecture, where water pollution was particularly serious, the installation of such systems was mandated by ordinance, and the entire community stepped up its efforts to preserve water quality. The crisis in Tokyo Bay also provided an opportunity to change the mindset of local administrations and citizens.
In other words, the domestic wastewater problem was not merely a "byproduct of daily life" but a mirror reflecting the structural distortion of the city. In contrast to the pollution era of the Showa period, which was symbolized by factory smokestacks, the environmental problems of the early Heisei period were mainly fought over "household sinks. As the economy matured, the responsibility for protecting the environment also fell to individuals and communities.