Hydrochemical and Microbial Quality of Groundwater in Anchal Gramapanchayat, Kerala: A Comparative Study of Open Wells and Tube Wells

Groundwater serves as a major source of drinking water in many rural and semi-urban regions; however, its quality can be influenced by both natural processes and anthropogenic activities. The present study evaluates the physicochemical and microbiological characteristics of groundwater sources in Anchal Gramapanchayat, Kerala, with particular emphasis on comparing open wells and tube wells. A total of 40 groundwater samples collected during 2022-2023 were analysed for parameters including pH, electrical conductivity, total dissolved solids (TDS), alkalinity, hardness, salinity, free carbon dioxide (CO₂), and total coliform counts following standard analytical procedures. The results showed that pH ranged from 5.30 to 8.41 with a mean value of 6.56, while TDS values varied between 54.5 and 656.8 mg/L. Most physicochemical parameters were generally within the permissible limits of the Bureau of Indian Standards (BIS 10500), with the exception of salinity, which exceeded the recommended limit in a few samples. However, significant variations were observed in microbial contamination. Open wells exhibited substantially higher total coliform counts (mean 831 ± 412.85 MPN/100 ml) compared to tube wells (7.15 ± 8.91 MPN/100 ml), indicating severe microbial contamination in shallow groundwater sources. Statistical analysis revealed that differences in physicochemical parameters between the two sources were not significant, whereas total coliform counts showed a highly significant difference (p < 0.001). Multivariate analyses including correlation analysis, Principal Component Analysis (PCA), and hierarchical cluster analysis further indicated that microbial contamination is largely independent of hydrochemical factors and mainly influenced by surface-related contamination sources. The findings highlight the greater vulnerability of open wells to microbial pollution and emphasize the need for regular monitoring, improved sanitary protection of wells, and effective groundwater management practices to ensure safe drinking water in the region.