7.Supply of Drinking Water with Clean and Safe

Ministry of Health, Labour and Welfare in Japan is established the drinking water quality standards of 46 items to keep up the supply of drinking water with clean and safe(Table 1). To respond to the standards, all the water utilities have fully introduced the works of improvement of water treatment facilities as well as introduction of necessity operation management. On the other hand, the water quality laboratory of water utilities is periodically conducting in order to measure for water quality whether tap water meets the standards perfectly by these measures or not.

  Table 1. Water Quality Standards of Drinking Water


In case of exceeding concentration of the standards, it is necessary to clarify the causative factors and take measures against prevention. In regard to prevention measures, the modification of operation management of the treatment plant is in the case a good solution or construction and improvement of facilities for water purification plant are also another ways. Water utilities are continuously required constant efforts to clear 100 per cent for drinking water standards to supply clear and safe tap water.

1)Items Relating to the Comfortableness of Water Quality and Monitoring
As the items of supplement for the drinking water quality standards, two types of guideline were established and water utilities are carrying a proper monitoring after the new drinking water standards, if it is necessary. One is the guideline value for the " Items Relating to the Comfortableness of Water Quality" (thirteen items such as 2-Methylisoborneol etc.) aiming at higher quality water corresponding to the public needs. The other one is the guideline values for the "Items Relating Monitoring" (thirty-five items such as Dioxin etc.) to ensure the safety of drinking water even in future. In addition the pesticides consisting of 26 items that may be used at the golf course are also monitoring appropriately, if it is necessary.

2)Revision of Drinking Water Quality Standards and Improvement of the Facilities of Water Supply
Drinking water quality standards of water supply is always renewing by introducing of the latest scientific approach, such as toxicity information, etc. Water works facilities are strongly requested to match the new drinking water quality standards to supply good quality and safe tap water even in future ages.