The following table summarizes, and simplifies, the requirements of the drinking water-quality standards listed to allow simple comparisons to be made. However, the requirements and recommendations within the standards quoted are complex and cannot be fully summarized in a simple table. In order to fully understand the requirements of the standards quoted, it is essential to refer to the source document. The listing is incomplete, particularly with respect to American Standards for organic chemicals.

The European Directive and British legislation includes mandatory parameters and indicator parameters.

USA Standards are classified into three categories: Primary health-based standards that are mandatory for all states; secondary standards, affecting aesthetics or that cause cosmetic effects, that are not mandatory; and health advisories, estimates of acceptable concentrations that are not legally enforceable. The system is complex and changes as standards are introduced and revised on the basis of additional knowledge, particularly for organic chemicals. In the table, only primary maximum contaminant levels (MCLs) and Secondary Drinking Water Regulation values are listed. The primary parameters also have guideline MCLs. For some parameters, the standard is a treatment technique rather than a numeric value. However, the technique is also associated with a maximum allowable concentration for the parameter.