Plastic water bottles bad for health?

I read that chemicals can be leached into the water. But i also saw the word Re-used a lot. Does this mean its only bad if i use the same exact water bottle multiple times or drinking from the same brand. I asked my dad and he said he heard its only if the bottle is left in the sun... The bad part is the water where i live taste like crap so the plastic bottles are all we have and im worried about drinking it now.