Background & objectives: Microbial, physical and chemical characteristics of drinking water depending on the type and quantity is the basis of water as whether it would be drinkable . In addition, each of the above mentioned characteristics has a great impact on quality enhancement, increase of acceptance level and threat on consumer health. Regular monitoring on quality of urban drinking water network and the remediation of old pipes has also essential role on human health. The purpose of this study is to know the value of physical, chemical and microbial parameters of Lahijan urban drinking water according to the type of pipe from distribution network and urban structure and to compare their values with national and international standards.

Methods: In this research based on 3 types of asbestos, galvanized and polyethylene piping, 50 Samples were taken on May and June 2012 from drinking milk houses and public places. Parameters including chlorine residue and pH were determined and microbial analyzes were also done. Possible effects on health and the properties of bulk water were questioned from users through the questionnaire.

Results: The amount of residual chlorine and pH were in the range of 0.2-0.5mgL^-1 and 6.74-7.40, respectively. The averageof residual chlorine and pH were 0.235±0.097 and 6.88±0.14, respectively. None of the specimens tested for coliform bacteria contamination was seen.

Conclusions: Based on the results of the questionnaire and public Dissatisfaction of the municipal drinking water, continuous chlorination and water quality have to be monitored more closely.