Canals in Suzhou are used by locals for washing clothes, riding boats, and washing vegetables and meat to drink or collect rubbish. However, the canals have become dirty because people wash items directly in the water, construction debris enters it, and some rubbish is thrown in while others do not care about keeping the water clean. The document discusses how locals in Suzhou utilize the canals for daily activities but also identifies reasons why the water has become polluted over time.