Influence of Water Source Switching on Water Quality in Drinking Water Distribution System
水源更换对给水管网水质的影响研究

This study investigates the regularity of the change on the physical and chemical water qualities in the distribution system during the process of water source switching in A city. Due to the water source switching, the water quality is chemical-astable. Because of the differences between the two water sources, pH reduced from 7.54 to 7.18, alkalinity reduced from 188mg?L-1 to 117mg?L-1, chloride (Cl-)reduced from 310mg?L-1 to 132mg?L-1, conductance reduced from 0.176S?m-1 to 0.087S?m-1 and the ions of calcium and magnesium respectively reduced 15mg?L-1 and 11mg?L-1; residual chlorine changed while the increase of the chlorine demand and the water quantity decreasing at night; the changes of pH, alkalinity and residual chlorine brought the iron increased to 0.4mg?L-1 at the tiptop, which was over the standard. The influence of the change of the water parameters on the water chemical-stability in the drinking water distribution system is analyzed, and the controlling countermeasure is advanced: increasing pH, using phosphate and enhancing the quality of the water in distribution system especially the residual chlorine.