Are the plastic bottles safe to reuse?

Yes, Plastic bottles are safe to reuse - as long as you dont fill very hot water, which melts the wall of the bottles. If bottle gets melted, avoid such bottles, as it might have release some chemicals in to water. (But, I have no proof to say that).

I am not an expert but I know that we shouldnt use reuse bottled water bottles for tab water because tab clorine is added to tab water which chemically react with the material used in manufacturing the bottled water bottles in way harmful to humans. Please verify!