Fact 1: Treating water is used to remove harmful substances before drinking.

Fact 2: Boiling is the most reliable way to treat contaminated water.

Given the two facts above, answer the question "Boiling can make water less what to drink?" with the following options: 
- germs
 - safe
 - energy
 - pure
 - harmful
 - dangerous
 - wet
 - heat


 

     harmful    