Abstract
When selecting drinking water projects today, funds are usually allocated depending on their impact measured in increased coverage. This approach is however misleading, since rather than the increased coverage at a given time, the increased coverage multiplied with operational years should determine how funds are spent. The concept of allocating funds by Water-Person-Years allows for an assessment which incorporates the operational time frame of a project. The logic result of Water-Person-Years calculations is that it becomes clear that more of the donated funds have to be spent on operation and maintenance in order to increase the efficiency of development aid.