Distributive effects of increasing block tariffs. the case of a mid-size city in France
Résumé
Consumer NGOs, local elected representatives and the media in France have recently favoured the idea of a water tariff that would be both incentive to conserve and social. Based on the evolution of the potable water share of the tariff in one of the first cities which adopted such a tariff, we calculated the distributive effect of successive changes on 9 types of housing units: single family, and condominiums of 10 and 100 apartments, where households would consume 75, 100, and 120 m3/yr. After some evolutions, the results show that all households benefit from a slight water bill reduction, and the bill is identical for the 3 housing types for the same consumption. This slight reduction leads to hypothesize that the new tariff might not be justified. A detailed analysis raises several critical observations going against a simplistic vision of progressive tariffs. But the tariff also results in large increases for large consumers, some of whom consider exiting the service and drilling their own well… This type of analysis should be done before any tariff change, given the complexity of factors involved in water bills.