[paper in French] In Brittany, water policy give little results compared to the money involved. Compared to northern European countries the French government don’t enforce the economic principles of the water framework directive (WFD). WFD defines the environmental target as an economic optimum which maximizes the collective value or minimizes social costs. Further, WFD says that water policy has to enforce cost recovery and polluter-pay principle (PPP). WFD economic principles are compared to the French policy for reducing animal pollution which is based on hypertrophic set of regulation and reject of PPP. This explains why producers don’t have incentives to reduce pollution by using least cost solutions like manure spreading. We suggest to limit the state’s paper to defining and enforcing standards via the PPP and to suppress the obstacles to manure spreading.