which water is good for drinking hot or cold.

There is no evidence that drinking cold water is bad for your health. Both cold and room temperature water will keep you  hydrated. Drinking warm water has its own benefits. Such as heaping digestion and toxin removal.  Staying hydrated has proven benefits for your mental and physical health. 

Boiling water makes it safe to drink in the event of some type of  biological  contamination. 

Bringing water to a rolling boil for 2 minutes is the  simplest way to consume.