This dataset presents comprehensive physicochemical measurements of raw groundwater utilized by Kathmandu Upatyaka Khanepani Limited (KUKL) across the Kathmandu Valley, Nepal. Collected from 60 operational groundwater sources between September 2023 and January 2024, the data include spatial coordinates , temperature, pH, dissolved oxygen (DO), and concentrations of critical parameters: ammonia (0.1–3.0 mg/L), arsenic (0.2–1.5 mg/L), iron (0.15–7.5 mg/L), nitrate (5–37.5 mg/L), phosphate (0.025–1.0 mg/L), chloride (0.0038–62.72 mg/L), and hardness (16–280 mg/L). All samples tested negative for E. coli. The dataset reveals significant spatial variability, with arsenic and ammonia exceeding Nepal Drinking Water Quality Standards (NDWQS) in urban areas, while iron and phosphate levels indicate localized contamination hotspots. These primary data support groundwater quality assessments, geospatial modeling, and policy interventions for sustainable water management in rapidly urbanizing regions.