Two wetland systems were tested to clean polluted water, using different materials and plants. The systems removed organics, nitrogen, phosphorus, and coliform bacteria. The first stage wetlands removed 39-97% of organics, 11-83% of nitrogen, and 20-100% of phosphorus. The second stage wetlands further removed 4-85% of organics, 16-86% of nitrogen, and 1.4-100% of phosphorus. Plants absorbed some nitrogen and phosphorus. Nitrification was key for nitrogen removal. Shock periods affected organics and nitrification in first stage wetlands but not in second stage wetlands. Resuspension of particles reduced performance in second stage wetlands. Coliform bacteria were reduced in second stage wetlands. Different materials and plant structures improved removal efficiency. This study shows that constructed wetlands can effectively treat polluted surface water.