A total of 254 humans and 489 domestic animals living on farms in the Lublin province (eastern Poland) were examined for the presence of antibodies against Toxoplasma gondii using, respectively, the ELFA and direct agglutination tests. In parallel, 182 samples of potable water, mostly from shallow household wells, were taken on farms and examined for the presence of T. gondii by microscopy and PCR. The frequency of seropositive reactions in farm inhabitants (66.9 percent) was significantly greater (p < 0.01) compared to the reference group of 39 healthy urban dwellers (41.0 percent). A highly significant positive correlation was found between the age of examined farm inhabitants and the rate of positive reactions with Toxoplasma antigen (p < 0.0001). Among domestic animals, the greatest frequency of seropositive reactions to T. gondii occurred in cats (75.0 percent) and dogs (53.6 percent), less frequent in cattle (33.8 percent) and hens (33.5 percent) and the least frequent in pigs (17.9 percent) and ducks (21.2 percent). The presence of T. gondii was found in potable water samples taken from water intakes on farms: in 12.6 percent of samples by microscopy, and in 22.5 percent of samples by PCR. Among 19 water samples taken from bathing places on the territory of the Lublin province, 2 samples positive for T. gondii (10.5 percent) were found by microscopic examination and confirmed by PCR . The presence of live parasites in water samples was demonstrated by the isolation of Toxoplasma gondii strains in mice. By use of RFLP -PCR it was found that the majority of isolated Toxoplasma strains (78.0 percent) belonged to clonal type I which is most virulent for humans and animals. Although no statistically significant relationship between the presence of T. gondii in water and occurrence of seropositive reactions in farm inhabitants and/or domestic animals could be found, the above-mentioned data suggest a potential role of potable water in the spread of toxoplasmosis in the rural environment.