Although a body of studies is available on the classical methods used for preparing drinking water free of bacterial and other microorganism contamination, a spare number of such studies were carried out, on testing of the natural volcanic mineral, zeolite. Therefore, this study intended to examine the effect of a promising natural zeolite, clinoptilolite, on the removal of bacteria from water samples taken from two wells present in two different regions of the province Erbil/Iraq, Nowruz and Sebardan. Five water samples of each region were tested before and after treatment with the clinoptilolite to isolate and enumerate viable microorganisms for total bacterial count (TBC). A batch system technique for automating and processing the samples from the wells was adopted. The first experiment treated the five samples separately with 1, 2, 3, 4, and 5 grams of clinoptilolite for 1 hour.  In the second experiment, all five samples were treated with 1 gram of zeolite but exposed to the treatment for 1, 1.5, 2, 2.5, or 3 hours. The TBC of the water obtained from the two regions (Nowruz and Sebardan) before treatment with zeolite were 19.4 and 8.6 colony-forming units (CFU) respectively, whereas the results after treatment with zeolite were, 4.8 CFU and 2.00 CFU, respectively. The results also showed that the most effective treatment caused the highest reduction in the CFU number which was with 1 gram of zeolite for three hours of contact time. The result indicated a significant effect of natural zeolite on removing the bacterial contamination from well water. Also, it showed that the water of the Nowruz region is more contaminated than that of the Sebardan region.

Keywords; Natural zeolite, removing bacteria, Total Bacteria Count.