The Act is formulated to ensure the quality of drinking water sources, improve public drinking water quality and ensure population health. The regulations of other laws shall apply to those matters not regulated by this Act.

In this Act, “competent authority” refers to the Environmental Protection Administration, Executive Yuan, at the central government level, the municipal government in special municipalities, and the county or city government in counties or cities.

In this Act, “drinking water” refers to water supply intended for human consumption. Types of drinking water include the following:
1. "Tap Water", which refers to health public water supply subject to the Water Supply Act that is channeled and supplied by water pipes and other facilities.
2. Water from community-installed public water supply equipment.
3. Water provided by sources treated by stationary continuous water supply equipment.
4. Other water designated by the central competent authority.
Drinking water sources are as follows:
1. “Surface water body” refers to water, in part or in whole, existing in rivers, lakes, reservoirs, ponds and other systems.
2. “Groundwater body” refers to water in the groundwater aquifer.
3. Other water bodies designated by the central competent authority.

In this Act, “drinking water equipment” refers to equipment subject to the regulations of the Water Supply Act, community-installed public water supply equipment, stationary continuous water supply equipment provided by public or private premises to the public for drinking, and other equipment designated and announced by the central competent authority.