Tap water quality standards

Water quality standards for tap water are stipulated by Ordinance of the Ministry of Health, Labour and Welfare in accordance with Article 4 of the Water Supply Law. "Water quality standard items" are defined for 51 items.
In addition, 27 items have been specified as “water quality management target setting items” and 46 items have been specified as “needs to be considered”.

Tap water must conform to water quality standards, and inspection is required by the Water Supply Law.
Water quality standard items are defined for 51 items, which are divided into items related to health and items related to the properties that tap water should have.

Standards have been set so that people can drink tap water for a lifetime (generally 70 years) does not affect their health.

Standards have been set to prevent color, turbidity, smell, etc. when using tap water as domestic water, or to prevent management problems of water supply facilities such as corrosiveness.

It is a document that contains standard values and explanations for each of the 51 water quality standards.

Although it is not a water quality standard because the evaluation of toxicity is provisional and it has not been detected at a concentration that is used as a water quality standard in tap water until now, the target value is set as an item to be noted in water quality management Has been done.

Items that cannot be classified into water quality standard items and water quality management target setting items because the toxicity evaluation is not determined or the amount of water in purified water is unknown.

Specific reference values for each item are posted.