In continuation of the preceding work on the water quality of the moat around the Imperial Palace in Tokyo, which is considered important as source of drinking water during emergency, yearly changes in the quality of moat water were measured and detailed examinations were made of the moat in two places during August, 1974. The moat was divided into five or six sections of equal distance, and water was sampled from upper and lower layers of each section. Laboratory tests were also made on removal of nutrients from moat water by filtration. It was thereby found that the quality of moat water did not differ greatly among sampling stations, and between upper and lower layers, so that measurement would be sufficient by sampling at one or two stations in each moat. Characteristic pattern of water quality was the high correlation between DO and pH, and this was especially so in November when the correlation coefficient was γ=0.765 and the regression line, Y=4.962X+0.272. Filtration was found to remove over 50% of total nitrogen, total phosphorus, and COD, and that removal of phytoplanktons from the moat will decrease nutrients in the moat water.