Comparing the efficiency of an activated carbon filter in filtering spring and tap water

Point-of-use (POU) filters are increasingly promoted as an alternative to bottled water, yet the extent to which they improve already high-quality drinking water remains uncertain. This study evaluated the performance of a commercial activated carbon (AC) block POU filter (“Filter A”) on tap and spring water under laboratory conditions. Filtration reduced turbidity (tap water: 0.112–0.066 NTU; spring water: 0.300–0.163 NTU), although all values fell within a very low range (<0.3 NTU) and should therefore be interpreted with caution. Small increases in pH and electrical conductivity were observed. Ion chromatography showed that most major ions were unaffected by filtration, with chloride the only ion to exhibit a statistically significant reduction (p < 0.05). Aluminium concentrations were generally below the analytical quantification limit and did not permit definitive conclusions regarding filter performance. All measured parameters complied with UK drinking-water standards before and after filtration. Overall, Filter A maintained drinking water quality while producing modest improvements in selected physicochemical parameters. These findings suggest that POU AC filtration may offer a practical alternative to bottled water for households already supplied with compliant drinking water, potentially reducing reliance on single-use plastic bottles.