The effect of community activities on water qualities of the Bangpakong River were investigated. Water from three different areas, Huasai temple, Thayai market and Sothorn temple, were sampled for quality monitoring for its physical, chemical and biological properties during July-September 2004. Analysis of variance was used for data analysis, and Duncan's Multiple Range Test was applied for means comparison at 95% confidence level.The results showed that ranges of dissolved oxygen, ammonia, nitrite, nitrate and orthophosphatephosphorus in all stations were 4.10-6.35, 0.022-0.156, 0.012-0.050, 0.084-0.299 and 0.004-0.047 mg/L, res the large food market, had the lowest water quality. Sothorn temple, the well-known tourist temple, had water quality in the middle of the three stations. Huasai temple, the agricultural site, had the best water qualities. The differences of water quality may be caused by the differences of community activities. The other parameters of this study could not clearly indicate the resons for the difference on water qualities.However, water quality from three areas met the Surface Water Quality Standard, class 3. Bangpakong River, the main river of Chachoengsao Province, is not only the source of water supply for households consumption as well as agricultural and industrial activities, but also receives untreated waste water from households, markets and industrial estates. Consequently, unless wastewater has been treated properly before discharging into the Bangpakong River, there will be water pollution in the near future.