This paper presents the results of a geochemical and isotopic study of technogenic soils and acid pool waters in the abandoned mine tailings pile and its potential impact on the adjacent farmers’ wells at the village of Serwis (south-central Poland). The acid tailings pools showed strong trace element and REE signals. These acid pools were featured by the predominance of medium rare earth elements (MREE) with a strong positive Gd anomaly. The technogenic soils also revealed a MREE roof-shaped pattern, but with distinct positive excursions in Gd, Sm, Eu and Ce. The δ34S-SO42– signatures of acid pool waters (mean of 1.3 ‰) were close to those of soils and pyrite (means of 2.3 and 3.2 ‰, respectively). The waters of four farmers’ wells exhibited nearly the same δ34S-SO42– values (0.7–4.0 ‰) as the nearby acid pool waters (0.3–3.1 ‰). The similar δ34S isotope signatures combined with the highest contents of dissolved SO42– (181–577 mg/L) in these wells suggest that the tailings pile is a potential source of SO42– derived from pyrite weathering. This relationship may also be evidenced by a spatial (site) variable dendrogram that groups these four wells into one cluster at the linkage distance (Dlink/Dmax × 100) < 53.