A PPP is only feasible (for the public sector and private operator) if it is economically and financially sustainable. Financial sustainability depends first on whether there is sufficient demand for the contracted service to sustain consumer willingness to pay, or a governmental acknowledgement that it needs to support the service through subsidisation because people who cannot pay need the service (for this reason, accurate tariff-setting that reflects demand is essential).
Economic sustainability can be affected by the economic activity the partnership generates. For example, if it uses local labour, stimulates new entrepreneurial activity, and creates new opportunities in the informal sector, the partnership is likely to attract community support. This would also have the effect of creating more demand. In this manner a project could have many spin-offs, which in turn become factors that sustain or even accelerate its momentum.