- Use that plastic bottle to just fill up and drink out of at home or at your desk. If the water doesn't sit in the bottle for a long period of time, it's way less likely that it will absorb the chemicals in the plastic (like bisphenols, because BPA isn't the only one out there). So feel free to use it throughout the day if you are drinking from it and refilling it regularly.
- Along those lines, don't let water sit in it for long periods of time. If you normally only use the water bottle when you go on hikes over the weekend, or when you head to the gym, don't leave water sitting in it all week and assume that next time you grab it a few days later the water inside will still be fine. The longer the water hangs out in the bottle, the more time it has to start soaking up the chemicals from the plastic walls. So, if you use it for your gym workouts, start with fresh water at the beginning of your routine, then drink it all. Or, after your workout, use any leftover water to water a plant or tree or something. Don't just let it sit for days - which I may or may not be guilty of.
- Don't leave it sitting in the sun either. Plastics like BPA or BPA replacements are more likely to seep into water when they are exposed to UV light - like the sun. So, on a day you are going to hang out at the beach or picnic in the park, grab a glass or stainless steel bottle and leave the plastic one at home.
- BPA also is super sensitive to acidic liquids. That means that if you are packing lemonade or coffee or even a sports drink, go for glass or stainless steel. They don't react to acid so won't leach any chemicals into your drink. Also, they are easier to clean and won't smell like coffee or lemonade for days after you've washed them like your plastic bottle might. Same is true for things that are fatty, so no chocolate milk or protein drinks either.
- Leave your (empty!) plastic water bottle in your car as a backup bottle. If you are running errands and get thirsty, filling up the reusable plastic bottle is still way better than buying a bottled water at a corner store - this article explains why.