If the water is clean enough, plants and animals can live in it and we can use it to produce drinking water.
River water contains all kinds of things, and there are many different substances in the Rhine. Some substances are not good for the water. So when is the water quality bad? Rhine water is dirty if there are too many harmful substances floating in it or dissolved in it, such as metals. This even applies to tiny particles of copper and zinc that are so small that you cannot see them without a microscope. But agricultural toxins like fertilisers, pesticides and medicines can also be harmful.
But the water must not contain too many plant and animal nutrients either. For example, too much algae will grow if the water contains too much fertiliser, and this is harmful to some types of plants and animals.
People cannot breathe underwater, but there is oxygen in the water. Not much, but enough for some creatures to survive.
The Rhine does not contain oxygen everywhere, and levels of oxygen vary. Sometimes there is not enough oxygen in the water, for example at places where there is too much fertiliser. This also means that the water quality is not good.
You can understand that it is difficult to ensure that the quality of Rhine water is always good in all places. But that is what we want. This is why the countries in the catchment area are working together to make the Rhine clean and keep it clean.
The quality of Rhine water is already much better than in the 1970s. It contains fewer metals and other harmful substances. Oxygen levels have risen.
But more can and must be done!
The countries in the catchment area want water quality to be good enough at all places in the long term. For the sake of the environment, and for our sake too. If they manage this, the following three things will happen:
1. Rhine water can be used for drinking water.
2. The Rhine is clean enough for us to catch and eat the fish that swim in it.
3. Everything that eventually ends up in the sea is less harmful.