To provide a low-cost turbid water treatment system.

When raw water is detected to be highly alkaline by a pH meter 11, a first flocculating agent containing polyacrylamide chloride and calcium chloride is added through a line L80 to a transfer route L2 to a solid- liquid separator 20 of the raw water where the raw water is subjected to a separation of solid from the liquid. The settled sludge is removed from the raw water in the solid-liquid separator 20 and thereafter a dilute sulfuric acid is added through a line L111 to a transfer route L4 of the separated water to a separated water tank 30 to neutralize only the separated water.