Sensitivity analysis of field test kits for rapid assessment of bacteriological quality of water

Bacterial testing kits are designed to provide rapid and cost-effective solutions for testing the bacterial contamination in potable water with reasonable accuracy. In this study, the culture method of bacteriological examination was used to critically evaluate the sensitivity of three different bacteriological test methods, namely, the Colilert-18h method, H₂S Test Medium (Powder) K019 and Bacteriological H₂S Strip Test, to provide an appropriate end-point use. Bacteriological sensitivity results of Colilert-18h were compared with those of the culture method. Once the Colilert-18h was found to be very sensitive to total coliform counts (TCC), the sensitivity analysis of the other two field kits was carried out. Results obtained from Colilert-18h showed that it is a highly sensitive and reproducible method as corroborated by the results of the spread plating method. Subsequently, the Colilert-18h method was used as a standard for critically evaluating the sensitivity of two available field kits, namely, H₂S Test Medium (Powder) K019 (sensitive for ≥4 TCC) and Bacteriological H₂S Strip Test (sensitive for ≥30 TCC), within 24–48 h of incubation, as suggested in their procedures. Thus, H₂S Test Medium (Powder) K019 is recommended for routine field testing for coliforms, as it is able to detect Salmonella, Citrobacter and other bacteria simultaneously.