Preliminary evaluations of potential sites for deep-well wastewater injection characteristically make use of existing data from deep boreholes drilled for other purposes. Unlike new drilling and logging operations specifically designed to address site-assessment needs, the quality of existing data may be questionable and requires special attention. In the present study, the desired features of a subsurface reservoir for wastewater injection are defined and a screening procedure for potential reservoirs is presented. Typical problems associated with data from deep oil- and gas-test wells are discussed, and guidelines for screening data of rock permeability and formation-water pressure, salinity and temperature are presented. These problems, as well as solution approaches, are illustrated for two different reservoirs, selected as potentially suitable for deep-well wastewater injection in west-central and northern Israel.