Data on the environmental requirements and pollution tolerance of 300 common species and varieties of freshwater diatoms was compiled from 48 references. The following parameters were considered: pH, nutrients, salinity, organic pollution tolerance (saprobien system), current, general habitat, specific habitat, seasonal distribution, temperature and geographical distribution. A consensus of opinions for each parameter was established for most taxa. It is suggested that this compilation be employed to evaluate data from plankton and periphyton samples collected for the assessment of water quality.