Seasonal changes in bacterial numbers of the Laghdomeh qanat in Saman - Shahrekord and probable sources of contamination

The Laghdomeh qanat is located in Saman in the north west of Charmahal-Bakhtiari and is one of the major water resources of the area. The aims of this study were to monitor water quality of this qanat and to determine seasonal effects on it. Thirteen wells along this qanat were sampled on a bi-weekly basis during spring and summer 2005. The water quality was determined by the standard most probable number method (MPN). The mean range of MPN 100 ml-1 for total coliform was found 37-270 in spring and 24-186 in summer. For faecal coliform, it was 26-110 and 4-31 MPN100 ml-1 in spring and summer, respectively.The bacteriological analysis revealed that all the samples collected from 13 different wells were contaminated with coliforms and faecal coliforms. with regard to bacteriological quality of public, semi public and private drinking water systems, the water should not has coliforms detectable per 100 ml, but bacterial contamination in this qanat exceeds the standards and must be considered as an infected source of water. In this study there was no positive correlation between water temperature and bacterial counts, but rainfall during spring and poultry farm appeared to be main affecting factors.

Keywords:

Bacteria , Contamination , Faecal , MPN method , Laghdomeh qanat