Water is an absolute necessity of life as well as a universal solvent. It contains dissolved materials and suspended particles even in its natural state. The quality of drinking water is rather a complex issue and involves various disciplines. Contaminants in drinking water present public health risk. Intermittent supply and contamination resulting in several gastrointestinal and other manifestations are the main concern of the population and health workers. The risk of outbreaks of waterborne diseases is high. Pollution originates from contamination of drinking water with domestic sewage as well as from industrial wastes, ultimately causing the deterioration of quality of both surface and ground water, as both are interdependent. The most important pollution sources were found in the distribution network due to cross contamination with sewers, illegal connections and corrosion.
The objectives of this study was to assess the quality of drinking water in two urban communities (Islamabad and Rawalpindi) called twin cities, served by different sources from surface (including Simly, Khanpur, Rawal, Said pur, Shahdra, Korang and Noorpur supplies) and ground waters (tube wells, wells and borings), and to attempt to identify the source(s) of illness due to drinking water.
A total of 503 clinical specimens (rectal or stool specimens of children under five year age) were analyzed qualitatively for their bacteriological studies. During the interviews of the parents of the patients, questionnaires were filled by them about all the information of their water consumed alongwith their case histories. Then water samples from the homes of the patients were analyzed qualitatively and quantitatively for physico-chemical and bacteriological parameters. After discussion with the officials of the authorities of both the cities responsible for water supplies, other sampling plan was formulated so that all types of water supplies of all the area should be represented and analyzed. So, a representative sample of 1006 families was selected and studied by analyzing their water samples and verifying pollution levels in the microbiological and chemical settings. The quality of water reaching the tap was emphasized along with the source distribution points. Here questionnaires were also filled by the residents of both the cities, from whom water were sampled or not, randomly, to know about the general public opinion. These water samples were of the origin, surface and ground water supplied by the government sector as well as the ground water of private sector.
Results indicated that children under 5 year's age were the most affected. Water contaminated by total coliform and faecal coliform bacteria along with different pathogens and potential pathogens were also detected at magnitudes several times higher than the permitted standards. Bacteria isolated from clinical specimen were the same as were isolated from the water consumed by them and these bacteria were the members of Enterobacteriaceae such as total coliform, faecal coliform, including E. coli, Salmonella, Shigella, Klebsiella, Proteus, Serratia, Enterobacter, Citrobacter etc., Staphylococcus, Pseudomonas, Enterococcus and Bacillus. These similarities between the isolates from both the types of samples confirms the correlation between water samples and the clinical specimens along with the questionnaire filled up by the general public about their drinking water and health.
Moreover, presence of these biological faecal pollution indicators along with the physico-chemical parameters involved in pollution like nitrates, nitrites, ammonia, phosphates, and extraneous matter confirmed faecal pollution. Physicochemical parameters including temperature, pH, electrical conductivity, extraneous matter, hardness, total dissolved solids, turbidity, Ca, Cu, Fe, Pb, Mn, Ni, K, Na, Zn, chlorine, chlorides, F, pH, Mg, ammonia, nitrites, nitrates, DO, P04 and S04 were analyzed.
Higher concentrations of parameters indicating faecal pollution and corrosion were of major concern. Absence of residual chlorine in most of the samples showed improper treatment and risk of contamination through the distribution system. Presence of high amounts of Lead (max. 2.789 mg/litre) indicated deteriorating condition of piping network. Approximately all the samples were positive for Lead. Statistical analysis showed a significant difference for most of the parameters while comparing government and private ground waters. Results indicated that ground water may be the main contributor of the contamination. Evaluation of drinking water quality supplied by government sector to the urban population of Islamabad through physicochemical analysis reflected somewhat satisfactory situation, as most of the parameters were within WHO guideline values (Annex 2 & 3) except a few.
Evaluation of drinking water quality supplied by government sector to the urban population of Rawalpindi through physicochemical analysis reflected non-satisfactory situation, as most of the parameters were above WHO guideline values (Annex 2 & 3). The faecal pollution indicator contaminants were found to be present, confirming faecal pollution. Bacteriology of clinical and water samples showed similarities and hence confirmed that the source of infection was drinking water. Detection of corrosion products like Lead in alarming amounts demands serious attention towards the improvement of distribution system. Private borings are comparatively less safe than government ground water supplies due to their chlorination and depth (private borings are too shallow). Public health and personal hygiene about the potable water safety and its hazards should be publicized. Water treatment plants should be run by experts and well trained personnel. Biological monitoring should be coupled with physicochemical monitoring to establish a long-term history of the source. There is a need of periodic monitoring, adequate treatment and corrosion management. Safety of water at the tap should be the prime priority of the government.