A water treatment system includes a water treatment unit and insulators. The water treatment unit is provided in an intermediate portion of a water passage allowing target water to flow, and produces bactericidal factors in the target water utilizing a discharge. The insulators are provided at an inflow side and an outflow side of the water treatment unit, respectively, and electrically insulate the water flowing to and out of the water treatment unit from the water treatment unit. The insulator at the inflow side sprays the target water to insulate the water. The insulator at the outflow side allows the target water to fall down from the water treatment unit to insulate the water.