The Catingueiro, Cristalino and Ligeiro Rivers, present in the eastern region of Cianorte, Paraná, Brazil, are under constant influence of industrial effluents and agrochemicals. In 2022, the public supply of this municipality will be made by waters of the Ligeiro River, and the sites predicted for abstraction are close to the sites of confluence of the Catingueiro River and the Cristalino River with the Ligeiro River. We evaluated in two periods of 2020, based on different parameters, the water quality of the Catingueiro River at two sites, P1 and P2 (P2, upstream of the confluence), the Cristalino River in one site, P3, and the Ligeiro River at two sites, P4 and P5 (P5, downstream of the confluence). Levels of nitrite, nitrate and sulfate in waters were within the range set by law. All points had a high concentration of fluorides and phosphato in the two collections. In P1, in both collections, a high concentration of copper was found.  P1 and P2, in the second collection, presented high levels of aluminum. Silicon was detected at all sites. Waters were phytotoxic to L. sativa and cytotoxic to the root meristems of A. cepa. Physical-chemical and toxicity analyses suggest a compromise in water quality. These data are an alert to the public authorities of Cianorte and Paraná regarding the anthropic actions carried out in these rivers and alert the sanitation company to carry out a preliminary and periodic analysis of the waters in order to know the contaminants present before treating them.