Monitoring of Coliforms and chlorine residual in water distribution network of Rawalpindi, Pakistan

The present study was undertaken to examine the drinking water quality of Rawal Treatment Plant, Rawalpindi and its distribution network by collecting samples from eight different locations. The aim was to determine potential relationship between the presence of microorganisms and chlorine residual in the distribution network. Quantification of chlorine residual, turbidity, standard plate count (SPC), fecal and total coliforms by Most Probable Number (MPN) was performed. Three different forms of chlorine were measured at each sampling station such as free chlorine, residual chlorine, chloramines and total chlorine residual. A critical evaluation of data presented indicated that pH generally ranged from 7.02–7.30; turbidity varied from 0.34–2.79 NTU; conductivity fluctuated from 359–374 μS/cm; and TDS values were found to be ranging between 180–187 mg/l. Station # 7 was found to be most contaminated. The value of total chlorine was found to be 0.86 to1.7 mg/l at Station # 3 and 6, respectively. Highest standard plate count was 62 CFU/ml at Station # 7. Totalcoliforms were less than 1.1 MPN/100 ml at almost most of the stations except at Station # 3 where it was found to be greater than 23.0 MPN /100 ml. Overall aim of this study is to create awareness about contamination of drinking water in the water distribution networks and to make recommendations to provincial agencies such as EPA, CDA and WASA that regular monitoring should be carried out to ensure that the chlorine residual is available at consumer end.

[1]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[2]  Wesley O. Pipes,et al.  Relationships between standard plate counts and other parameters in water distribution systems , 1983 .

[3]  Charles N. Haas,et al.  Microbial alterations in water distribution systems and their relationship to physical–chemical characteristics , 1983 .

[4]  M. S. Mohan Kumar,et al.  Water Quality Parameter Estimation in Steady-State Distribution System , 2003 .

[5]  R Otson,et al.  Comparison of trihalomethane levels and other water quality parameters for three treatment plants on the Ottawa River. , 1981, Environmental science & technology.

[6]  Ramon G. Lee,et al.  Factors promoting survival of bacteria in chlorinated water supplies , 1988, Applied and environmental microbiology.

[7]  H. Gorchev,et al.  Water chlorination : environmental impact and health effects , 1978 .

[8]  James M. Montgomery,et al.  Water Treatment Principles and Design , 1985 .

[9]  Ramon G. Lee,et al.  Giardia and Cryptosporidium spp. in filtered drinking water supplies , 1991, Applied and environmental microbiology.

[10]  N. Ram,et al.  Chlorine Residual Monitoring in the Presence of N‐organic Compounds , 1984 .

[11]  J. K. Reilly,et al.  Relationship of bacterial counts with turbidity and free chlorine in two distribution systems , 1983 .

[12]  S. Jilani,et al.  Drinking water quality in the city of Karachi , 1998 .

[13]  Chungsying Lu,et al.  Spatial Diversity of Chlorine Residual in a Drinking Water Distribution System , 2004 .

[14]  Dominique Gatel,et al.  Fate of Escherichia coli experimentally injected in a drinking water distribution pilot system , 1996 .

[15]  H. Kitazawa.  Keeping residual chlorine and decreasing unpleasant odor caused by disinfection of tap water , 2006 .

[16]  Deli Chen,et al.  Spatial variability of shallow groundwater level, electrical conductivity and nitrate concentration, and risk assessment of nitrate contamination in North China Plain. , 2005, Environment international.

[17]  M. Lechevallier,et al.  Effect of turbidity on chlorination efficiency and bacterial persistence in drinking water , 1981, Applied and environmental microbiology.

[18]  J. Rook.  Chlorination reactions of fulvic acids in natural waters , 1977 .

[19]  V. P. Olivieri,et al.  Stability and effectiveness of chlorine disinfectants in water distribution systems. , 1986, Environmental health perspectives.

[20]  M. Snead.  Benefits of maintaining a chlorine residual in water supply systems , 1980 .