Some are purely economic, some environmental and others embracing social issues, such as equity, affordability, universal coverage. Regulatory' functions do not necessarily have to be in the hands of a single institution. However, they need to be clearly spelled out and allocated to avoid overlap and incoherence. International experience shows that regulation of WWS can have various solutions and be embodied in a wide variety of institutional arrangements and legal instruments, depending on the particular characteristics of the country under consideration (see various publications, including Marques and Simoes, 2010).