Formaldehyde was detected in the purified water of some purification plants in the Tone river system in May 2012.Some water utilities suspended water supply and 870,000 people was affected. Also, the water quality accident raised many issues regarding crisis management of drinking water quality because it had specificity of the causative substance, hexamethylenetetramine. Hexamethylenetetramine is high hydrophilic, so it cannot be reduced by powdered activated carbon. Without odor, color and high toxicity, it is difficult to find the substance at the river. And the most unique point is that it is formaldehyde precursor. By dealing with the issues, the tap water quality management can be improved further more.

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We have identified the cause of the formaldehyde pollution that occurred in the Tonegawa River system in May, 2012. We analyzed 10 river water samples that were collected in the Edogawa River using a liquid chromatography/ tandem mass spectrometry (LC/MS/MS) and a liquid chromatography/ ion-trap time-offlight mass spectrometry (LC/IT-TOF-MS). As a result, hexamethylenetetramine was detected in all the water samples. Further, significant relationship was observed between the hexamethylenetetramine and the formaldehyde concentration in the same sample (r²=0.9576). Furthermore, formaldehyde concentration calculated by the reaction formula was very similar to the measured formaldehyde concentration in each sample. Therefore, we concluded that the cause of the formaldehyde pollution was the inflow of hexamethylenetetramines in the river system. Further, we focus the future issues on the management of unregulated chemicals in drinking water.

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Formaldehyde concentration in treated water in some water treatment plants along the Tone River exceeded the Drinking Water Quality Standard in Japan in May 2012. Water supply was halted in five cities and approximately 870 thousand people were affected by this accident in Tokyo metropolitan area. It was finally proved that, over 10 tons of hexamine, a formaldehyde precursor, was transported into a waste treatment factory without an appropriate notice from the emitting chemical company and discharged from the waste treatment factory. It then contaminated the river water, introduced into water treatment facilities, and transformed into formaldehyde by chlorination in water treatment. We hereby describe governmental risk management framework in this situation and show future direction.

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Discussion was conducted at a national investigative commission on the Tone River system water pollution accident by formaldehyde occurred in May 2012. The objectives of the commission were establishment of preventive and restoration measures against this water pollution case based on the appropriate legislation development. Discussion results at the commission and the following countermeasures were summarized from the viewpoint of chemical and waste management in this paper. Briefly, aqueous monitoring for hexamethylenetetramine (HMT), a precursor of formaldehyde and information transfer of HMT-containing wastes during waste treatment processing have been strengthened.

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Regarding risk management for emergent water quality accidents, the author believes better risk governance is not achieved by mere total optimization of systems of law regarding water management but by the flexible coalition among respective optimized systems. A questionnaire survey on the perception for water supply suspension was conducted after the water quality accident by formaldehyde in May, 2012. As preliminary results, 43% of respondents did not want suspension of water supply even if the water did not satisfy the standard values. If the water for oral intake purpose could be ensured by other sources such as bottled water, 86% did not want the suspension. These results suggested public anxiety for adverse health effects by the water that exceeded the standard values even if the exceedance did not cause adverse health effects. Risk communication on meaning and effect of “exceeding the standard values” should be important to mitigate the anxiety.

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Authors reviewed several examples and made a proposal on the application of Best Available Techniques (BAT) and Best Environmental Practices (BEP) as a tool of chemical management. The final purpose of the chemical management is both of chemical safety and public sense of security. In general, chemical safety is achieved by complying with the government regulations. The public sense of security is achieved only when the chemical safety by chemical industries is further improved in their responsibility. BAT and BEP is one of the good tools for the responsibility. In other words, we proposed that BAT and BEP can make chemical safety more reliable and responsible. This is a goal of sustainable chemical management in the future.

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In this paper, damage with surface leakage caused by break accident of water supply pipe is interpreted as flood problem. Reduction of flood risk is immitigable. Consequently, assessment for extent of the damage is important before the accident occurs. Urban storm water is drained mainly through sewage system. Even if comparable surface leakage occurs, the damage varies according to conditions, discharge capacity of sewage system and terrain condition. It is estimated that the extent of flood with surface leakage can be larger than that of 50 year return period rainfall through case study analyses. Also, it is suggested that occurrence frequency of surface leakage caused by pipe break accident is higher than by heavy rainfall. Therefore, this paper pointed out the necessity to assess flood risk for replacement planning in the future.

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