PROBLEM TO BE SOLVED: To provide a water cleaning method capable of easily cleaning the water of lakes and marshes, preventing the outflow of soil and easy in arrangement or maintenance, and equipment therefor. SOLUTION: A plurality of planting units 1a for hydroponic culture are arranged stepwise in the vicinity of lakes and marshes 3. Water containing nutritive salts pumped up from the lakes and marshes is supplied to the planting unit 1a positioned at the uppermost stage and distributed from the planting unit 1a positioned at the uppermost stage to the planting unit 1a positioned at the lowermost stage to grow plants in the planting units 1a to remove nutritive salts. COPYRIGHT: (C)2004,JPO
