The National Environmental Sanitation Service (SENASA) is a body under the Ministry of Public Health and Social Welfare (MSPBS) created by law 369/72, of December 1, 1972.

It develops various functions in environmental sanitation activities: planning, promotion, execution of works tending to extend the supply of drinking water and sanitation. It has jurisdiction over localities of up to 10,000 inhabitants.

The National Environmental Sanitation Service will be able to build water systems and basic sanitation services in indigenous settlements, peasants or other human conglomerates, with budgetary resources of national or international source.