The present investigation focuses on the chemical and biological contamination of drinking water as a case study in El-Taquaddum area in Sinai. This area use to suffer from deficiency of clean drinking water. The present study investigated the effect of residual chlorine deterioration and the storing period on the chemical and biological quality of drinking water. The results obtained revealed that storing drinking water for long time in closed or open storing tanks deteriorate the residual chlorine that affected on the chemical characteristics and biological contamination of drinking water. Correlation between the closed storing tanks and the open ones in terms of the chemical and biological quality of drinking water as affected by the residual chlorine was studied.
This investigation reveals that the residual chlorine in drinking water is the controlling factor to prevent the presence of colifrom bacteria. The continuous supply of freshly chlorinated water is important to keep the level residual chlorine on the safe border. However, increasing the storage time of the water affects dramatically on the available residual chlorine, and thus affects on the presence of several contaminants including insects, coliform bacteria, and fungi. Therefore, it is strongly recommended to avoid storing the drinking water in open tanks in order to prevent any chemical and/or biological contamination. Nevertheless, filtration through regular home filter that consists of ceramic filter and UV device could eliminate the presence of contaminants including suspended chemicals, bacteria, insects, fungi and turbidity.