The Promise of Water to the Faucet: Japan's Water Supply and Increased Regulation 1993-1995

The Promise of Water to the Faucet: Japan's Water Supply and Increased Regulation 1993-1995
In the early 1990s, Japan's water supply system entered a phase of integrated management from "source to faucet. The starting point was a complete revision of water quality standards in 1993. The Ministry of Health and Welfare (MHW) made major revisions to the standards themselves and established a framework of complementary monitoring items, which went into effect in December 1993. This was a signal to reorganize practices that included not only water purification and treatment but also management at the water source.

This trend was accelerated by the so-called "Two Laws on Water Supply Sources" in 1994. The Ministry of Health and Welfare's "Law Concerning the Promotion of Implementation of Water Quality Conservation Projects for Raw Water Supply" and the Environment Agency's "Law on Special Measures for Conservation of Water Quality in Water Source Areas for the Prevention of Specific Water Use Disruption" were promulgated one after the other, institutionalizing the authority and procedures for water source conservation and monitoring for local governments and businesses. Thereafter, the control of pollution factors in water source areas and the introduction of advanced treatment on the water purification side began to move simultaneously.

At the core of the tightened regulations was the control of trihalomethane. This byproduct of the reaction between chlorine disinfection and organic matter in the water was clearly defined as a total trihalomethane level of 0.1 mgL or less, and became a pillar of management. The standard values were based on the Council's report at that time, and the basic line has been maintained in subsequent reviews.

In the field of technology, advanced water purification treatment using a combination of ozone oxidation and biologically-activated carbon has been in full swing in many areas. The two-stage system, in which ozone oxidizes odorants and precursors and biological activated carbon adsorbs and biodegrades them, will take root as a trump card for both controlling trihalomethanes and improving drinking quality. The Bureau of Waterworks of the Tokyo Metropolitan Government has officially explained the significance and effectiveness of advanced water purification and pushed it to become a standard technology in the metropolitan area.

Thus, from 1993 to 1995, the renewal of water quality standards, the implementation of the Water Source Two Law, and the spread of advanced treatment were all connected by a single line. The system showed where the responsibility lies and the figures to be observed, and the technology was brought down to the field in response to the system. The system showed responsibility, and the technology responded by going downstream to the field. The promises of that era remain the foundation that supports Japan's water supply today.