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 even though they know that its can cause the dirty canal and its can affect health and economy country credit ,they are lazy so they find the easiest way to throw a rubbish. Everyone wants to solve this problem ,but actually all of the dirty canal problems have caused by ourselves. So, If we want 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.