As reflected in the title, the Guidelines are of an advisory nature and are intended to be used by national or regional authorities as a basis for the development of drinking-water standards and regulations appropriate to their own socio-economic and exposure situation. The Guidelines clearly recognize the desirability of adopting a risk-benefit approach (qualitative or quantitative) to national standards and regulations. The establishment of drinking-water quality standards by individual governments must follow a very careful process in which the health risk is considered alongside other factors, such as technical and economic feasibility. Standards achieve nothing unless they can be implemented and enforced. When establishing national standards, consideration must be given to the practical measures that will need to be taken with respect to finding new sources of water supply, instituting certain types of treatment, and providing for adequate surveillance and enforcement.