As has been recently recognised by the European Water Framework Directive (WFD), an adequate urban water management demands a correct water-pricing policy. In particular, the article 9 of the WFD suggests a full cost recovery, mainly as far as urban and industrial uses are concerned. This is a request that, due to historical reasons and vested interests, most of the south European countries (like Spain) are far from being able to fulfil. Developed countries certainly find themselves in an even worse situation, and with complicated socio-economic circumstances, they find serious difficulties to even recover partially the costs. Politicians most frequently establish urban water pricing policies. Since they are usually more concerned about their short-term popularity than for the long-term technical results, urban water supply systems are poorly managed. The real fact is that water prices respond mainly to socio-economic and political factors than to any other rational criteria. However a sustainable water supply management requires the inverse approach: the standards to be fulfilled must be initially defined while the water tariff should be such that it would allow satisfying the established goals.