It feels like such a healthy, safe choice, doesn’t it, grabbing that bottle of water? But if that bottle’s plastic, there’s a high chance your hydration also means ingesting harmful chemicals that are the opposite of your healthy goals. The best solution is probably to avoid plastic bottles altogether, but what do we do when it’s the only option? The answer comes from Creative Tips— just flip the bottle over.

See those letters there? They tell us exactly which chemicals are in that plastic, and if you know what chemicals are there, you know whether there’s anything leeching into your water you’d be better off avoiding. Here’s a handy guide to help you decode those letters.

Safe

HDP Or HDPE
This number-one recommended type releases essentially no chemicals into your water. It’s also used in things like milk jugs, detergent bottles, and toys, and is easy to recycle, making it one of the better plastics for the environment, too. If you must drink from a plastic bottle, make this kind the one you choose.

Unsafe

PET Or PETE
This kind of plastic is common in bottles, but it shouldn’t be. It can release heavy metals, carcinogens and other chemicals that affect hormonal balances.

PC Or Non-Labeled
Probably the most well-known kind of plastic, PC stands for “polycarbonate” and serves as kind of a catchall for plastics that don’t fall into other categories. It’s also one of the most dangerous, with studies showing it leaks BPA into the water, food and other drinks it contains. BPA can disrupt your endocrine system, so avoid this one – and all unlabeled plastics – above all.

PS
PS stands for “polystyrene.” Ring any bells? If it reminds you of Styrofoam, it’s because it’s the plastic that forms the popular food-container material: coffee cups, egg cartons, clamshell take-out boxes, etc. Unfortunately, it also has been shown to release carcinogenic substances. While it’s obviously less common in water bottles, it’s still good to be aware.

PVC Or 3V
Another plastic that isn’t too popular in typical water bottles, PVC is commonly used for things like cooking oil, even though it’s been shown to release two harmful, hormone-altering chemicals.

Clearly, there are several types of plastic, and Creative Tips’ list mentions even more common ones that are questionable, but uncommon in water bottles and unproven to leech any chemicals. The best we can do is educate ourselves so that we can make sure all of our decisions are informed, thoughtful ones— and this list is a good start! So tell us— do you know anything else about plastic bottles and the different kinds of plastic? How do you try to avoid unnecessary chemicals and protect yourself, your family and the environment?