Widespread and intense zones of silicified, propylitic, and argillic alteration can be found in the Ç an volcanics of Biga Peninsula, northwest Turkey. Most of the springs in the study area surface out from the boundary between fractured aquifer (silicified zone) and impervious boundary (argillic zone). This study focuses on two such springs in Kirazlı area (Kirazlı and Balaban springs) with a distinct quality pattern. Accordingly, field parameters (temperature, pH, and electrical conductivity), major anion and cation (sodium, potassium, calcium, magnesium, chloride, bicarbonate, and sulfate), heavy metals (aluminum, arsenic, barium, chromium, cobalt, cupper, iron, lithium, manganese, nickel, lead, and zinc), and isotopes (oxygen-18, deuterium, and tritium) were determined in water samples taken from these springs during 2005 through 2007. The chemical analyses showed that aluminum concentrations were found to be two orders of magnitude greater in Kirazlı waters (mean value 13813.25 lg/L). The levels of this element exceeded the maximum allowable limits given in national and international standards for drinking-water quality. In addition, Balaban and Kirazlı springs are [55 years old according to their tritium levels; Kirazlı spring is older than Balaban spring. Kirazlı spring is also more enriched than Balaban spring based in oxygen-18 and deuterium values. Furthermore, Kirazlı spring water has been in contact with altered rocks longer than Balaban spring water, according to its relatively high chloride and electrical conductivity values.Water-rock interaction is an important topic influencing the water quality as well as human health. Particularly in altered systems, these interactions are more important for local inhabitants using water for drinking purposes because the water in such systems might contain increased levels of certain elements that are potentially detrimental to human health. Thus, these interactions should be assessed carefully in areas of complex geology where rocks formed as a result of hydrothermal system are predominant.Hydrothermal fluids carry metals in solution, coming either from a nearby igneous source, from leaching of subsurface rocks, or both (Henley et al. 1984). These fluids then alter other rocks, changing their mineralogy and chemical composition (Nicholson 1993;Verma et al. 2005;Pandarinath et al. 2008). Complex zoned alteration patterns have been well documented from a large number of important hydrothermal ore deposit types, including submarine-volcanogenic massive sulphide (Finlow-Bates and