CORROSION ON DRINKING WATER DISTRIBUTION SYSTEMS AND ITS INFLUENCE IN THE WATER QUALITY

摘要

Variations in drinking water quality were evaluated for different pipe materials which are used in secondary distribution systems. The research was carried out in four pilot loops constructed of carbon steel, galvanized steel, copper and another one in PVC for control purpose. The systems have been evaluated during a period of twenty-six weeks. Water samples are analyzed in the entry and exit of each system, with a retention time of 24 hours. The results obtained for six months indicate that parameters such as pH, turbidity, dissolved oxygen, conductivity and total dissolved solids changed differently according to the pipe material. The corrosion rate of the carbon steel was higher than for copper and galvanized steel. The values were 451μm.y~(-1) for carbon steel, 35μm.y~(-1) for galvanized steel and 27μm.y~(-1) for copper; whereas the corrosion rate in the control loop (PVC) was 0.08μm.y~(-1) for stainless steel. The carbon steel pipe caused the greatest change in water parameters; also carbon steel presented the greatest formation of products on the surface and water attack.