Apart from the typical chemical constituents of H2O, rainwater will also contain whatever is in the atmosphere where the clouds build up and distribute the rain.
carbonic and nitric acids, dissolved gases in the atmosphere.
Waste is poured into the ocean water, and it turns into rain, making it polluted rainwater.
The pH of rainwater is normally from 6 - 6.5. Acid rain is rain with a pH of 5 and below.
rain water has vitamin B12