Question

Why is water pollution a concern if water is continuously cycled through earth's systems?

Answer 1

There are things like human disregard for the environment, volcanoes, storms, algae blooms, and earthquakes that are all considered contributors to water pollution.

Answer 2

It is a concern because if dirty water evaporates, then it condensates it would could pollute the atmosphere decreasing the Ozone Layer. When it rains it could also destroy crops.