Abstract: Polluted industrial waste water having a high chemical demand for oxygen and fine particles in suspension is purified using the following steps: directly heating and evaporating the polluted water without subjecting it to the usual prior steps of mechanical separation such as sieving or decanting; separating sludges from the evaporated water; condensing the evaporated water; subjecting the condensed evaporated water to a physico-chemical purifying process of the coagulation-flocculation type; and filtering the purified condensed evaporated water. The purified water is pure enough to be recycled through a dyeing works. The installation includes an evaporator (10) which is preferably built in several stages with the vapor from each stage other than the first being used to evaporate the polluted water in the next stage.