Summary:

The paper presents the reliability of the sewage treatment plant operation for Tuchów commune. The research was carried out from January 2005 to
December 2006. The following sewage pollution ratios were physico-chemically analyzed: BOD5, CODCr, total suspended solids. In order to define the proper treatment plant's operation, the reliability coefficient was calculated (RC) for each of the tested indexes. The empiric reliability was presented. The amount of transgresions of the admissible index values presented in the water-law permis-sion was described. Moreover, the efficiency of the ratios' decrease in the tested period was defined.
The carried out research showed the high efficiency of the pollutants' amount decrease: BOD5 - 90,7%, CODCr - 86,6%, total suspended solids - 90,5%. The calculated Reliability Coefficients RC of the analyzed indexes amounted respectively: for BOD5 - 0,52, for CODCr - 0,31 and for total sus-pended solids 0,62.