The so-called contingent valuation method is frequently used to quantify the benefits brought about by the implementation of a project with environmental impacts. This method uses data collected in field researches conducted among the potential beneficiaries of the project. The objective of this paper is to show how to use information contained in existing studies for similar projects as a possible way to reduce the costs of the evaluation process. The paper proposes that such information, which supplies preliminary indicators for some crucial parameters, allows to narrow the scope of choices among projects of the same type in new places. The type of project selected for analysis is the construction of a sewage system in several middle-size cities in Brazil.
