A nutriculture system enables the circulation of a nutrient solution while preventing the proliferation of pathogenic bacteria and can promote the growth of plants effectively and steadily while preventing the change in components of the nutrient solution. A water treatment apparatus for sterilization and purification purposes is compact in size. Specifically, the nutriculture system can circulate a culture solution, which is a liquid fertilizer, between a nutrient solution tank and a culture bed. The water treatment apparatus is disposed between the nutrient solution tank and the culture bed, sterilizes and purifies only the culture solution that flows through the culture bed and includes a unit having an ozone supply function for supplying ozone to the culture solution, an ultraviolet ray irradiation function for irradiating the culture solution with ultraviolet rays, and a photocatalyst-acting function for allowing a photocatalyst to act.
