As the whole human population needs drinking water for sustaining life the provision of a safe water supply is a high priority issue for safeguarding the health and well-being of humans. The production of adequate and safe drinking water is the most important factor contributing to a decrease in mortality and morbidity in developing countries. The World Health Organization (WHO) reported that nearly half of the population in these countries suffers from health problems associated with lack of drinking water or the presence of microbiologically contaminated water. In the developing countries more than 60 percent population has no access to pure drinking water. The basic question in the production of drinking water is how to rid drinking water of potentially dangerous microorganisms and chemical without introducing new hazards that might pose new and different threats to human health. Water treatment and distribution system, if not properly operated and maintained can be a source of disease outbreak affecting large populations. Therefore, the monitoring and surveillance of quality of raw water sources as well as treated water need to be enhanced. Water is a very good solvent, hence it dissolves some toxic and hazardous substances, producing water pollution problem posing many public parameters of interest for water quality assessment and nitrates and nitrites are out of them. Furthermore, turbidity and nitrate concentrations peak during heavy rain episodes. An increase of nitrates in water is often associated with farming fertilizer, pesticide or poor sanitary activities. The WHO guideline for nitrates in drinking water is established to prevent methaemoglobinaemia (blue babies), which is lethal in babies and can be potentially hazardous with health risks for considerable groups of people and depends on the conversion of nitrates to nitrites and wells which were shallow, dug of located on large farms, or springs were more likely to have elevated concentrations of nitrates.
Table 2: Percentage of population with access to safe drinking water (2000) [17]
Country
%
Country
%
Country
%
Country
%
Country
%
Albania
97
Algeria
89
Azerbaijan
78
Brazil
87
Chile
93
China
75
Cuba
91
Egypt
97
India
84
Indonesia
78
Iran
92
Iraq
85
Kenya
57
North Korea
100
South Korea
92
Mexico
88
Moldova
92
Morocco
80
Mozambique
57
Pakistan
90
Peru
80
Philippines
86
Singapore
100
South Africa
86
Sudan
67
Syria
80
Turkey
82
Uganda
52
Venezuela
83
Zimbabwe
83
The use of nitratecontaminated drinking water to prepare infant formula is a well-known risk factor for infant methaemoglobinaemia. Affected infants develop a peculiar blue-grey skin color and may become irritable or lethargic depending on the severity of their condition. The condition can progress rapidly to cause coma and death if it is not recognized and treated appropriately. Contamination of drinking water by nitrates is an evolving public health concern since nitrates can undergo endogenous reduction to nitrites (nitrate (III)), and nitrosation of nitrites can form N-nitrose compounds, which are potent carcinogens. This reduction process runs relatively fast in the alimentary canal of infants under the age of 6 months, so can lead among infants to the disease called methemoglobinemia (blue baby syndrome). There is a positive association between nitrates in drinking water and non-Hodgkin lymphoma and colorectal cancer. In 1986 WHO fixed the limit of the contents of nitrates and nitrites in drinking water, taking guidance from which Pakistani standards were developed. According to Pakistan Standards, fixed limits of the contents of nitrates and ...