The Effect of Pipe Materials on the Regrowth of Bacteria In Karaj Water Distribution Network

According to the collected information in 2002, Karaj city with an area of more than 166km2 and consisting of Central Karaj, Rajaeeshahr, Fardis and Mehrshahr has accommodated more than 1150000 population. Nearly 40 percent (407891 people) have just settled in Central Karaj. Water distribution to this population has been served by 49 wells and a water treatment plant with the production capacity of 180 litres per second and using a 25km transmission line and a 567.68km distribution network.In order to determine the effect of different kinds of materials used in Karaj water distribution system on the support of bacteria population growth, sampling strategy were designed to eliminate the effective parameters such as: water organic materials, turbidity, temperature, free residual chlorine in Galvanic, Cast iron ductile, Asbestos and Plyethylene from August 2001 to December 2002. The results showed that although in a uniform condition the amount of regrowth of bacteria in asbestos pipes was a little more than other mentioned materials, but the effect of water distribution system material because of the large amount of free residul chlorine, in 83 percent of the examined samples is not that much sensible and manifest. Howere, the effect of distribution network materials can not be mentioned as one of the effective factor on the regrowth of bacteria in a distribution system containing more than 0.2 mg/l free residal chlorine.