Question

give reason why distilled water doesn't conduct electricity whereas rainwater or tapwater does ?​

Answer 1

The availability of ions is very important to conduct electricity. Distilled water is a pure type of water which does not contain any ions in it. Whereas rainwater contains dissolved gasses such as SO2, CO2.

These gases dissolve in water to form some kind of acids like carbonic acids which dissociates to give ions. Thus rainwater is conducting electricity while distilled water is not conducting electricity.