Access to safe drinking water is essential to good health, a basic human right, and a component of effective policy for health protection. Improving the quality of local public water and waste services is one of the United Nations Sustainable Development Goals (Goal 6: Clean Water and Sanitation). This study aims to know the degree of satisfaction of domestic users who receive services related to water and waste in municipalities with less than 20,000 inhabitants in the province of Badajoz (Spain). We carry out this research because the perception of municipal services provided by the public administration is usually negative and deficient. The case study PROMEDIO, the consortium formula, is described as a successful partnership to improve the quality of local public water and waste services. For this purpose, a detailed analysis of the different aspects involved in the relationship between the users and the services provided is carried out. The consortium was found to increase citizens’ satisfaction with the services provided, given the close relationship between the municipality and the users.