our research is about dirty canal. because Thailand has a lot of the canal. There are some people who live near the canal, the factories and restaurants near the canal and they throw trash into the water. especially, the factories which discharged dirty water into the canal. All of these pollute water pollution and affect on the health of people in Thailand. Dirty canal is one of the big problem in Thailand for a long time and this problem have not been solved. This problem has occurred in the urban and rural that we can see them obviously. so, we choose the dirty canal to do our research