Environmental water monitoring is a systematic process of observing, measuring, and evaluating the physical, chemical, biological, and microbiological characteristics of water to determine its quality and suitability for different uses. Water monitoring is an important component of environmental health because contaminated water can transmit infectious diseases, cause chemical poisoning, damage aquatic ecosystems, and reduce the availability of safe water for drinking, agriculture, and industry. An effective water monitoring system provides reliable information about changes in water quality and helps authorities take timely measures to prevent pollution and protect public health. The main purpose of an environmental water monitoring system is to determine the existing condition of water bodies and identify changes over time. It helps in detecting sources of pollution, assessing the effectiveness of pollution-control measures, ensuring compliance with water-quality standards, and protecting communities from exposure to hazardous substances. Monitoring may be conducted in rivers, lakes, reservoirs, groundwater sources, wetlands, coastal waters, drinking-water supplies, and wastewater discharge points. A water monitoring system generally begins with the identification of the water body and the objectives of monitoring. The objectives may include assessing drinking-water safety, monitoring industrial pollution, determining the health of a river ecosystem, checking groundwater contamination, or evaluating the quality of treated wastewater. The monitoring programme should clearly define what parameters will be measured, where samples will be collected, how frequently monitoring will occur, and which methods will be used for analysis. Water sampling is a fundamental component of monitoring. Samples should be collected from representative locations so that the results accurately reflect the condition of the water body. Sampling sites may include upstream and downstream locations, industrial discharge points, drinking-water sources, agricultural areas, urban drainage channels, and groundwater wells. For example, if a river passes through an industrial area, samples may be collected before the industrial zone, near major discharge points, and several kilometres downstream. Comparing these samples can help identify the effect of industrial activities on river quality. Sampling frequency depends on the purpose of monitoring and the characteristics of the water body. Some programmes collect samples daily, while others may collect them weekly, monthly, seasonally, or annually. Continuous monitoring instruments can measure parameters such as temperature, pH, dissolved oxygen, turbidity, and electrical conductivity at frequent intervals. Regular monitoring is particularly important where pollution levels can change rapidly because of rainfall, industrial discharges, agricultural runoff, or sewage releases. Physical parameters provide basic information about water quality. Temperature influences chemical