An important hallmark of development is public wastewater facilities, which are vital in curbing the spread of infectious diseases and checking pollution. Europe leads in this regard. In the Netherlands, 99 percent of the population is connected to public sewerage systems. In the United States the portion is about 75 percent. Japan's rate, according to the Ministry of Internal Affairs and Communications, is 76.3 percent as of March 2013, though this number represents population rather than households. In almost all of Japan's major cities, the rate is close to 100 percent, but the farther away from cities you get the more the number drops. Tokushima Prefecture is the lowest, at 16.3 percent.
This isn't to say that Tokushima residents are in danger of contracting dysentery, only that the majority of people aren't hooked up to gessui (public sewerage systems), which bring wastewater to treatment plants. Most of such households have septic tanks, which in Japan are called jokaso. After the war, the demand for flush toilets increased exponentially, but there were not enough resources to build public sewerage facilities as quickly as people replaced their squat commodes with Western-style ones, so many people had to use septic tanks.
In the beginning, septic tanks used the itandoku-shori method, which meant that so-called black water from toilets was processed in the tank while so-called gray water from the bath and kitchen went straight into the environment. Special trucks would periodically drain the septic tanks and take the sludge to treatment plants. By 1969, the number of people relying on public sewerage systems was about the same as the number with septic tanks. Then, in the 1980s, when government standards were revised, new homes increasingly installed advanced jokaso using the gappei-shori method, which processed both black and gray water in a highly efficient manner.