The study focuses on a multi-indicator assessment of groundwater quality in south-western Poland with regard to its suitability for municipal and agricultural purposes. The Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI ) was applied to evaluate water for drinking purposes, while Soluble Sodium Percentage (SSP), Sodium Adsorption Ratio (SAR), Kelley Ratio (KR), Magnesium Adsorption Ratio (MAR), and electrical conductivity (EC) indices were used to determine its quality for irrigation. The analysis covered data from 26 monitoring sites collected between 2005 and 2024, taking into account spatio-temporal variability as well as the influence of natural and anthropogenic factors. The results revealed considerable variability in water quality, with CCME WQI values in 2024 ranging from 49.62 to 100. The most significant negative impact on water quality was attributed to iron (Fe), manganese (Mn), and ammonium (NH₄⁺), showing strong negative correlations with the CCME WQI (r = -0.898, -0.756, and -0.575, respectively). In some sites, exceedances of up to tenfold for Fe and fortyfold for Mn were recorded, which may pose risks to both human health and infrastructure. Irrigation suitability indices generally indicated good quality, although locally reduced suitability was observed, mainly related to elevated EC. The study demonstrates the necessity of a site-specific approach to managing groundwater quality, which takes into account local pollution sources and hydrogeological conditions. These findings could inform remedial actions, optimise water treatment and ensure the sustainable management of water resources in agriculture.