Analysis of physico-chemical parameters and bacteriology study of Vaigai river water Madurai district, Tamil Nadu, India-2025

The study aimed to evaluate the physico-chemical parameters of Vaigai River water at five selected stations in Madurai District, Tamil Nadu, during 2025. A total of 18 parameters including pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), alkalinity, hardness, calcium, magnesium, iron, chloride, nitrate, nitrite, phosphate, fluoride, sulphate and free ammonia were analysed following APHA (2005) standard methods. The results revealed considerable variations across stations, reflecting the impact of domestic sewage, industrial effluents and agricultural runoff. The pH ranged from 6.0 to 7.75, indicating slightly acidic to alkaline conditions. EC values varied between 474 and 520 µS/cm, while TDS levels ranged from 355 to 677 mg/L. Dissolved oxygen was consistently low (0.93-1.52 mg/L), whereas BOD (23.8-32.5 mg/L) and COD (60.3-81.2 mg/L) exceeded permissible limits, suggesting heavy organic load. Alkalinity (140-172 mg/L) remained below the undesirable limit for drinking water, whereas hardness (140-208 mg/L), calcium (35-52 mg/L) and magnesium (14.6-21.7 mg/L) showed moderate values. Chloride concentration (40-66 mg/L) was within BIS standards, while nitrate (3-8 mg/L), phosphate (0.3-0.8 mg/L) and sulphate (7-20 mg/L) indicated nutrient enrichment. Elevated iron levels (0.6-3 mg/L) at some stations exceeded acceptable limits, posing risks for potability. Overall, the results highlight that the Vaigai River water in 2025 is under considerable pollution stress primarily from anthropogenic activities.