Project scope can vary considerably, depending upon the type of project being proposed but it is important that the project scope should be clearly defined at the outset, with the objective of attracting private investment. An improperly defined project leads to overlooked costs, a mistake that happens quite often during economic and financial appraisal. For example, in estimating the costs of a water supply system, allowance should be made for insufficient yield of a groundwater source (which cannot be accurately predicted until the production well is dug), in which case another production well might have to be developed. There are no hard and fast rules but some consultants will opt to include contingency for another production well.
Furthermore, the project rationale and 'packaging' should be carefully considered. Thus, for example, whereas the water distribution network can be constructed through traditional means of public procurement, the source development and treatment could be packaged separately for PPP, under a bulk supply agreement.