Gjilan (42°27’48’’N 21°28’09.7’’E) is one of theseven biggest cities in the Republic of Kosovo. Water supply for this city isenough for reasons of functioning of two plants of water processing in the cityof Gjilan. One of the biggest plants for water is in Perlepnica village andanother plant with smaller dimension to supply drink water is in Velekicavillage. The main issue focuses on the water treatment plant in theVelekica village because the presence of manganese (Mn+2) as metalis always present in six underground springs. Quantity of Mn mg /dm3in groundwaters is out of norms allowed under WHO. The presence of this metal forces the water industry to use KMnO4continuously. In the water the present of this metal is from (0.05-0.0015) mg/dm3 during 2017 and January 2018 and after the manganese processing process isreduced to (0.11- 0.31) mg /dm3. While in the water treatment plantin Përlepnica village, there is no problem with heavy metals and the process ofprocessing continues today without any problems.