Abstract
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.
