Conclusion
From the method of research that we have chosen, the result is most of cause of the dirty canal caused by human such as waste water from home, shops and office building, wastewater industry, fertilizer used in cultural etc. Most of people have thrown rubbish into a canal. The dirty canal can affect not only health and economy but also country credit. Everyone wants to solve this problem ,but actually all of the dirty canal problems have caused by ourselves. So, If we need to stop water pollution in the canal, we need to start from ourselves. Let’s make Thailand’s canals is called The Venice of the east again.