[en] The people of Sta. Barbara in Iloilo, Philippines uses for cooking and drinking a brown-black artesian well water, which they believed has medicinal properties. The water has been shown to be rich in humic acid. There has been no reported deaths or diseases related to the consumption of the water. However, the opening of the Iloilo International Airport in the vicinity may catalyze the growth industries in the place and this in turn, may introduce inorganic xenobiotics to their groundwater supply. This study investigates using FTIR, the interaction of potential contaminant metals ions (Cd²+, Cu²+ and Pb²+) and humic acid. The carboxylic and phenolic groups, which are considered the primary binding sites for protons, metal cations and hydrophobic organic chemicals, are also approximated carboxylic and phenolic groups as 2.0534 and 1.5771 mmol g-¹, respectively. FTIR analysis of humic acid showed the acid related peaks (∼1710,∼1612 cm¹), the phenolic -OH related peaks (3400-3300 cm¹), and the amide related peaks (∼1612,∼1511 cm¹). Changes in these peaks were noted in the FTIR spectra of the metal-humate complex/salt. The spectra of Cd-, and Pb-humate generally showed changes in the phenolic-OH and acid-related peaks. The Cu-humate spectra, on the other hand, suggested a Cu-N coordination and an extensive decarboxylation in the humic acid structure. (author)