BPA is not found in every plastic, but may be found in some water bottle plastic. The EU and the EPA recommend a daily intake level of less than 0.05 mg/kg of body weight (equivalent to ~0.02 mg/ lb of body weight). So if you weigh 100 lb, then 2 mg/day is the limit.

I found a paper from the University of Cincinnati, College of Medicine from 2011 that reports that at room temperature, polycarbonate water bottles release 0.2 to 0.3 mg of BPA into a liter of water.

So, according to this study, a 100 lb person could drink 10 liters of bottled water or less per day to stay in the recommended limit.

I did some research on Google and found that it is very hard to find a concrete number on how much BPA is released. There are two reasons for this. First, the amount of BPA in a plastic is largely dependent on what type of plastic the bottle is made from. The bottles made from polycarbonate (they’ll have a #7 PC) on the bottom seem to have the highest concentrations of BPA. Polycarbonate is usually found as a hard plastic like a Nalgene bottle.

The amount of BPA leeched can also vary depending on the temperature and acidity the plastic is exposed to. When plastic (especially PC) is heated or placed in an acidic solution more BPA is leeched out, so a plastic bottle stuck in a cold and non-acidic landfill BPA will leech out very slowly. Consequently, make sure never to put hot coffee or orange juice in a Nalgene! (But you’re in 7th grade, so you probably shouldn’t be drinking coffee yet anyway, regardless of container.