Analysis of physicochemical properties, trihalomethane levels, and trihalomethane formation potential in Cagayan de Oro city's primary drinking water source

The raw and processed waters satisfied the Philippine, WHO, and USEPA standards for pH, conductivity, salinity, TDS, and TSS. While both waters exceeded the PNSDW total hardness threshold, the WHO does not consider this a health concern at the levels found in drinking water. Raw water turbidity exceeded the PNSDW, WHO, and USEPA regulations. Unlike total hardness, turbidity poses a health risk since it may stimulate microbial growth, leading to waterborne illness outbreaks. However, the processed or tap water's turbidity was well within the permissible limit, indicating that the treatment process is effective. The total trihalomethane (TTHM) of the processed water came out higher than the standard values for total trihalomethanes set by the PNSDW, USEPA, and WHO. On the other hand, the trihalomethane forming potential (THMFP) of the raw water was high as manifested by the high concentration of total trihalomethane (84 mg/L) produced after the simulated chlorination. The raw water high THMFP led to a processed water high THM concentration (41.7 mg/L). The total trihalomethanes are likely influenced by total organic carbon (TOC), turbidity, total hardness, total suspended solids (TSS), total dissolved solids (TDS), conductivity, salinity, and pH as indicated by statistically significant correlations.