The city of Lages (Brazil) is in the Santa Catarina mountainous region and has approximately 160,000 inhabitants. The Caveiras river is the primary source of water in the city. Rafaeli Neto et al. (2019) studied the hydrology of the Caveiras river and obtained information about its 2,416 km² watershed and 232 km of length from its source to the mouth. The authors claim this river has a sinuosity of 2.5 Km·Km⁻¹ in the sector where the raw water is captured. Additionally, they characterized the land adjacent to the river as a floodplain. Rafaeli Neto et al. (2013) built a map of the use and occupation of the Caveiras river basin, which is used as a water supply source for the city of Lages. According to the authors, the river spring area is where there is the highest forest index, decaying as the river advances. The fields represent 40–50% of the basin, with 4–5% reforesting. There is surface runoff of pollutants and the water itself when it rains, which increases the river flow and leaches sediments, increasing the turbidity and, consequently, the apparent color of the water. The region's climate is temperate (Köppen, Cfb), with evenly distributed rainfall and average annual rainfall ranging from 1,100 to 2,000 mm, with no dry season. Different conditions of raw water were found as the work was carried out over nine months because there was a significant change in the parameters when it rained due to solids being carried into the river. Therefore, the water quality varies, as demonstrated in the raw water characterization section (Table 1).