A report on a global survey of urban water tariffs has been released
This paper also examines the relations between tariffs and sustainability, efficiency and equity, using a unique data-set for 308 cities in 102 countries. Higher water tariffs are correlated with lower per capital consumption, smaller local populations, lower water availability, higher demand and a lower risk of shortage. Aggregating to the national level, higher tariffs are correlated with higher GDP and better governance.
The findings of the survey are available here: http://kysq.org/pubs/Zetland_Gasson.pdf