Why you shouldn't drink out of plastic
They leach chemicals, Drinking out of a plastic bottle could very slowly make you sick(Especially if left in the sun). If you've ever noticed a plastic water bottle tastes like plastic than that's because the plastic can 'contaminate' the water
Tap water has to meet certain and alot of standards. Bottled water doesn't have to meet these standards. This can actually make it less healthy then tap water or filtered water
Ofcourse we all know this one, It is bad for the environment. In one year we use 17 billion barrels of oil each year just to produce plastic water bottles. It's alot of non-reusable resources being used each year on something that is not necessary.
And land fills are full of water bottles. The water project predicts there are 2 million pet water bottles. Water bottles are recyclable but only 1 in 5 water bottles are
There are more reasons but these are the major ones. Learn more here: https://www.littlethings.com/dont-drink-bottled-water/