Hydrobiology is the study of living things and their processes in water. Much of modern hydrobiology is considered a part of ecology, but it also includes other areas like taxonomy, economic biology, industrial biology, and morphology. Recent studies on water bodies in Rajasthan for 2025 and 2026 show that the environment is under a lot of stress because of fast-growing cities, polluted industrial waste, and changes in the climate causing more evaporation. Water is essential for all living creatures, including plants, animals, and humans. It makes up more than 70% of the human body, and no living thing can survive without it. Water is also very important for daily tasks like cooking, cleaning, and transportation. However, the quality of water is getting worse due to the use of harmful chemicals and industrial waste. Things like household trash, dead organic matter, and dangerous chemicals are making clean water sources dirty, which is bad for people's health and the environment. Studies in Rajasthan show that the groundwater has high levels of fluoride, nitrates, chlorides, and total dissolved solids (TDS), which can cause health problems like hydrofluorosis. Surface water, like lakes and ponds, is suffering from eutrophication, which is caused by pollution from sewage and dirt, leading to too many nutrients like phosphates and nitrates, and changing the types of plankton, which harms the whole ecosystem and makes the water unsafe for drinking or farming. Scientists are studying various physical and chemical elements in the water, such as pH, electrical conductivity, BOD, and COD, as well as living things like phytoplankton and zooplankton, to understand the effects and find ways to protect these important, but stressed, water sources in the desert. Checking the physical and chemical features of water regularly is necessary to keep it clean. Parameters like temperature, total hardness, pH, sulfate, phosphorus, nitrogen, chloride, fluoride, dissolved oxygen, BOD, COD, total alkalinity, and TDS must be checked to determine the water quality. This report brings together review on water quality based on these factors, offering useful information for future studies and efforts to protect clean water.

Keywords: Limnology; Physicochemical characters; Biological parameters; OCPs; Heavy metals; Water bodies Rajasthan.