Four com. membrane water treatment plants were analyzed for their operability and reliability The reverse osmosis-based plants for purifn. of drinking water consists of coagulation with FeCl3,, flocculation, neutralization with HCl, two-stage filtration, two-stage permeation and disinfection with CIO2, (capacity 40 m(3)/h). Another plant for mine water treatment based on reverse osmosis yields drinking water with a capacity 800 m(3)/d. The microfiltration-based water treatment plant is used for purifn. of mine water used for techn. purposes. It includes oxidn. of crude water with KMnO4, disinfection with NaOCl and cleaning the capillary membranes with an air stream. Another plant uses microfiltration for purifn. of river water delivered as drinking water after addn. disinfection with NaOCl.