Evaluation of corrosion and scaling tendency indices in a drinking water distribution system: a case study of Bandar Abbas city, Iran

Corrosion and scaling is a major problem in water distribution systems, thus evaluation of water corrosivity properties is a routine test in water networks. To evaluate water stability in the Bandar Abbas water distribution system, the network was divided into 15 clusters and 45 samples were taken. Langelier, Ryznar, Puckorius, Larson-Skold (LS) and Aggressive indices were determined and compared to the marble test. The mean parameters included were pH (7.8 +/- 0.1), electrical conductivity (1,083.9 +/- 108.7 mu S/cm), total dissolved solids (595.7 +/- 54.7 mg/L), Cl (203.5 +/- 18.7 mg/L), SO4 (174.7 +/- 16.0 mg/L), alkalinity (134.5 +/- 9.7 mg/L), total hardness (156.5 +/- 9.3 mg/L), HCO3 (137.4 +/- 13.0 mg/L) and calcium hardness (71.8 +/- 4.3 mg/L). According to the Ryznar, Puckorius and Aggressive Indices, all samples were stable; based on the Langelier Index, 73% of samples were slightly corrosive and the rest were scale forming; according to the LS index, all samples were corrosive. Marble test results showed tested water of all 15 clusters tended to scale formation. Water in Bandar Abbas is slightly scale forming. The most appropriate indices for the network conditions are the Aggressive, Puckorius and Ryznar indices that were consistent with the marble test.