The principles are applied mostly through the National Duties Law that defines and sets the rates for water abstraction and water pollution charges. But, as discussed later, many users do not pay for water and water pollution, because they are either exempted, under-report consumption or pollution, or abstract water or discharge wastewater illegally. In the case of the Water-Pays-for-Water principle, the Law on Contributions for Improvements Generated by Federal Public Works of Water Infrastructure (Ley de Contribucion.es de Mejoras por Obras Publicas Federates de Infrastruclura Hidraulica) establishes the regulations and procedures for recovering the cost of public investments in water infrastructure but it has never been applied.