Things rot, then crumble and fall apart. And then comes the rain. The water in the rain tends to dissolve almost everything that needs to be cleaned up, leaving intact most things which do not need to be cleaned up. The tapping action of the individual raindrops hastens and promotes the clean-up process. The rain collects the refuse, then deposits some of it into the ground, where it is filtered and makes its way into the water table below.
Some water runs off into streams, which feed into rivers, which feed into oceans.
The process of evaporation extracts the pure water and draws it upward, where it eventually forms clouds and rains again. The residue not evaporated stays below, in the oceans. So we once again return to the core truth, as stated in the very first verse of the Bible. In the beginning God created the heaven and the earth.