A sputtered platinum thin film was fabricated by using photolithography, sputtering, and a lift-off method. The sputtered Pt grains were uniformly dispersed in the film as observed from FE-SEM images to form a compact film with fairly homogeneous size. Square wave voltammetry was used to directly detect Fe(III) with this electrode, typically at a working potential of 0.63 V (vs. Ag/AgCl). The method had a 90 ppb detection limit and worked in the 0.3–5 ppm concentration range. This value meets the requirements set by the World Health Organization. In addition, the stability and reproducibility of the electrode were superior (with RSDs of 3.363% for 5 repetitive measurements). For real tap and well water samples, the electrode gave the well-defined peak for Fe(III) without showing any enrichment in Fe(III). The results from real water analyses were in agreement with those obtained by the UV–Vis method. © 2019 Elsevier Ltd