The safety of drinking water is essential to human health. Many countries and regions according to their own economic situation, natural environment and cultural conditions, etc. have developed their own drinking water standards. And the most representative and authoritative the World Health Organization's quality standards, it is countries to develop national drinking water standard basis and foundation. In addition, the EU drinking water directive for the body, the Federal Environmental Protection Agency's Safe Drinking Water Act, are all meaningless the reference to drinking water quality standards.
一、World Health Organization's "Guidelines for Drinking Water Quality"
 World Health Organization (WHO) published "Guidelines for Drinking Water Quality"is a national drinking water standards to develop guidance documents, on behalf of the United Nations system in the drinking water quality and health position on the issue. Since 1983, has published "Guidelines for Drinking Water Quality, " first and second editions, and later after 8 years, from 90 developing and developed countries the participation of 490 experts in 2005 Published "Guidelines for Drinking Water Quality, " third edition (see Appendix V). The new "guidelines" third edition, replacing all previous versions of previously published earlier can be replaced by "international standards. "

WHO guidelines to develop water quality standards are:
 1、The control of microbial contamination is extremely important. Disinfection by-products on health is potentially dangerous, but the health risk than the imperfect sterilization is much smaller;
 2、Meet the "criteria" guideline value for drinking water is safe drinking water;
 3、Short-term water quality detection value exceeds the guideline values ​​does not imply that such water unfit for drinking;
 4、In the development of chemical guideline values​​, they need to be considered part of direct consumption, but also consider the bath or shower when skin contact or intake of volatile substances in part through the respiratory tract.

二、EC "Drinking Water Directive"
    Amended in 1998, "Drinking Water Directive"(98/93/EEC) lists the 48 quality indicators, divided into microbiological indicators (2), chemical indicators (26), indicating indicators (18), Radioactive indicators (2) categories. European countries in developing as an important reference for national water quality standards. And requested Member States to December 25, 2003, to ensure the quality of drinking water to the provisions of the Directive (bromoform, except for lead and trihalomethanes).

三、America's "Drinking Water Regulations"
    Federal Environmental Protection Agency in 1986 issued a "Safe Drinking Water Act Amendments, " provides for the implementation of the rules of drinking water quality plan, formulated the "basic national drinking water regulations and secondary drinking water regulations. " The legislation is the current U.S. drinking water standards (see Appendix VI), the provisions of the pollutants in drinking water maximum contaminant levels (MCL) and maximum concentration of pollutants target (MCLG). Target value refers to the maximum pollutant concentration of contaminants in drinking water is not unknown to human health or adverse effects of the maximum concentration, a non-compulsory health indicators.
   "National Drinking Water Basic Laws"(or national drinking water regulations) is mandatory standards, the public water supply system must meet the standards. The basic regulations in 2001 a total of 88 water quality indicators, listed in 5 categories; Microbial Indicators 7, disinfectants and disinfection byproducts 7, target 16 inorganic, organic indicators 54, radioactive indicators 4.
    "National Secondary Drinking Water Regulations, " the guiding standard is not mandatory. Used to control the water of beauty (skin, discoloration of the teeth) or sensory (such as smell, taste, color) affect the concentration of pollutants. EPA recommended but not mandatory implementation of secondary legislation, the states adopted the optional add as mandatory targets. The secondary drinking water regulations in 2001 listed a total of 15 indicators.

四.Japan's "drinking water quality standard " treatment
    Based on the existing water quality standards, Japan's latest drinking water quality standard was April 1, 2004 implementation of the water quality standards program (called water quality criteria) from 46 to 50, of which 13 new projects added, deleted By the project 9. In the new water project, divided into two categories; first to water quality criteria, 50; second goal of the project for the water quality management, 27.