Waste waters pollute rivers, lakes, seas and ground waters. This threatens the existence of life on Earth. Waste waters facilitate the growth of micro-organisms that consume oxygen, causing fish perishing and the growth of pathogenic microbes. This paper puts emphasis on the problem of environmental protection against waste waters generated by 'Duga Resa Cotton Industry'. The textile industry generates waste waters in the production process. Such polluted waste waters should be purified before discharging into watercourses. The method of pre-treatment or purification of waste waters in the textile industry can be a neutralization, oxidation or reduction procedure. Moreover, there are physical degradation methods (depositing, filtration, absorption, etc.), physical and chemical degradation methods (coagulation/ flocculation, aeration, extraction, combustion, osmosis, electrolysis, etc.) and biological degradation methods (aerobic, anaerobic, by means of activated carbon and fungi). The selection of the purification method depends on the composition and type of waste waters. Only after purification can waste waters be discharged into the sewerage. The law prescribes the quality of waste waters, thus raising the quality of people and environmental protection. [ABSTRACT FROM AUTHOR]