What if there was no water? What if we got so sick and died? What if we cleaned ourselves in dirty water with chemicals and acids? What if the animals died? These are the things that might happen if you don't clean the water.
One reason we want to clean the water is we do not want to have unhealthy bodies. We want to keep our circulatory system clean, or we will die. So we need to keep the water clean because we want our body to keep clean.
The second reason for this is we would not want to be dirty for the rest of our lives. If we clean ourselves in dirty water with chemicals and acids we will die. So we can prevent this from happening if you clean the water.
The final and last reason is because we would not want to kill the animals. If you give them dirty water they will die. We don't want to have them die of thirst. We want to keep them healthy so we need to keep the water clean.
In conclusion, I think we should clean the water because if we don't we will die, we will never be clean and all the animals will die.