We know what the dangers are. We are able to measure how large they are, and we know more or less where they come from. How do we resolve this? There are a few ways in which we try to improve water quality.
If we can make sure that less harmful substances end up in our waste water, soil and air, we don’t need to remove it from the water later on. That sounds easy, but how can we be sure that it happens?
We can do it by making agreements about the substances we use, and how much of them we use. And research might help us find other substances to use that are less harmful.
In farming, for example. Organic farming means that less harmful and environmentally substances are used.
We purify a lot of waste water at the moment, but things can always be improved. There are still harmful substances that we cannot remove from it. This is why scientists are always trying to find new and better ways of purifying water.