Water & Solutions Forum – Water Science, Processing and Maintenance



Water Use and Environment in Japan – Current State of Water Environment



Current state of water environment in Japan

 Due to the rapid expansion of industrial activities and the concentration of man-made cities during the post-war period of high growth, serious pollution of environmental water has progressed. In response to this situation, the water environment has been improving as a whole since the Basic Pollution Control Law was revised and the Water Pollution Control Law was enacted in 1965 and the environmental standards relating to water pollution and factory drainage standards were established.



Generation source

 The main sources of water pollution associated with daily life and industrial activities are shown in the table below. Drainage from daily life is also a heavy burden on the environment. Looking at the percentage of BOD load in domestic wastewater by source, it is kitchen 4, human waste 3, bath 2, laundry 1. As a measure for domestic wastewater, the construction of sewers and combined septic tanks (Johkaso) is being promoted. In addition, the pollution load that flows out from non-specific pollution sources such as urban areas, land development sites, and agricultural land due to rainfall, etc., and the pollution caused by the elution of nutrients from sediments that have sedimented and accumulated in the past are factors that contribute to water pollution in Japan.

表 水質汚濁の発生源 Table Sources of water pollution



Public waters

 Significant improvements have been seen in health items such as cadmium, which is a harmful substance related to human health, and the achievement rate in FY2013 was approximately 99.2%. On the other hand, the achievement rate of environmental standards [1] for BOD or COD, which is a living environment item, was 87.3% overall, 92.0% for rivers, 55.1% for lakes, and 77.3% for sea areas. The achievement rate is the ratio of the number of achieved water areas to the number of type-designated water areas. Since the enactment of the Water Pollution Control Law, rivers have been improving steadily, but the water quality improvement status of stagnant water areas (closed water areas), such as lakes, inland seas, and inner bays, is flat or is gradually improving.
 In closed water areas, it is difficult to exchange water with the outside and pollutants easily accumulate, so it is difficult to improve and maintain water quality, and the rate of achievement of standards is low compared to rivers and sea areas. In addition, new types of pathogenic microorganisms such as Christosporidium, environmental chemicals called endocrine disrupting chemicals, and water pollution from permeated water from waste disposal sites are becoming a problem.




 Groundwater is known to be contaminated with organochlorine compounds and nitrate nitrogen. Once the groundwater is polluted, it takes a long time to recover and it is difficult to take effective countermeasures. Groundwater pollution includes nitrates, nitrites, and gastrointestinal pathogens. Chromium (VI) compounds are the most common pollutants due to harmful substances, and mercury, cyanide, cadmium, arsenic, organophosphorus compounds, and lead have been reported in small numbers. Groundwater pollution by chlorine-based solvents has been confirmed to be widespread in Japan.

Posted: July 9, 2016
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