Does rainwater contain many fewer micro-organisms than river water?

Question

From watching many documentaries on micro-organisms, I can tell water typically contains quite a lot of them. But what about rainwater? (before it hits the ground). I know nothing about any micro-organisms that live in the sky or clouds. Does rainwater contain fewer, and less dangerous, micro-organisms?

Answer 1

Typically, bacterial organisms replicate quickly in stagnant pools of water. Additionally, since many bacteria that cause infection in humans and other animals are transmitted fecal-orally, groundwater is more easily contaminated by bacteria or parasites.

However, rainwater is still likely to contain bacteria, parasites, or contaminates and should still undergo the same level of purification as groundwater prior to drinking.