Happy Earth Day! Make Mother Nature happy with one of these reusable canteens. If you’ve ever wandered the aisles of any rec store, you’ve likely stumbled into the vast world of water bottles. Every shape, size and material line the aisles just to keep you hydrated throughout a sweat-burning workout. You want a purple BPA-free plastic bottle with a spouted nozzle and a handle? No problem. Or maybe a plain stainless steel variety with a removable cap? Sure thing.

With so many options, which is truly the best and safest choice? This Earth Day, do Mother Nature a favor. Instead of adding to the 38 billion non-reusable plastic water bottles piling into the landfills each year, start toting around one of these refillable thirst-quenchers.

Plastic water bottles vs. stainless steel water bottles

Plastic water bottles have received some negative press in the past for containing Bisphenol-A, a.k.a. BPA, a chemical linked to cancer. Fortunately, companies responded and most water bottles sold after 2010 are now BPA-free. However, it’s still important to acknowledge what type of plastic bottle you’re sipping from and also to take into consideration what those little numbers on the bottom of your bottle stand for. Disposable water bottles, which you can often pick up at the gas station or in packs of 24 at the grocery store, are labeled with a number 1 and are only meant for a single use.

Although washing and refilling these bottles seems like a smart choice for the environment, they are not durable enough to withstand multiple uses and often end up leaching unwanted chemicals into the water. To protect yourself and the environment, look for bottles labeled with the numbers 2, 4 or 5. Although these are prone to retaining odors and staining after constant use, they do not leach chemicals, are the cheapest bottle options on the market, and come in a variety of styles. So go ahead and be picky—there’s a perfect plastic water bottle out there with your name on it. No chemicals included.

Design for Living Stackable Water Bottle

This rectangular bottle stacks easily in the fridge and won’t roll around if you accidentally drop it in class (yes, we’ve all done that). Plus, the durable, commercial-quality plastic makes it odor- and stain-resistant.
Buy now: Amazon, $15

Brita Sport Water Filter Bottle

Now, you can have filtered water without the hassle of a pitcher. The built-in filter reduces the taste and odor of chlorine commonly found in tap water, while the contoured design and handle help you quickly grab for a sip in between circuits.
Buy now: Amazon, $18 for 2 bottles

Reduce WaterWeek

Fill these five BPA-free water bottles with up to have a week’s worth of water and have them conveniently waiting for you in the fridge. The lightweight bottles are easy to grab-and-go, and the bright patterns are sure to brighten up your office desk.
Buy now: Houzz, $20 for 5 bottles plus storing tray

Stainless steel water bottles

If you’re still concerned about BPA and the possible chemicals that could leach from a plastic bottle, opt for stainless steel. These bottles are constructed from culinary-grade stainless steel and are non-reactive, meaning they won’t shed harmful toxins when filled with H2O. However, be mindful not to confuse these canteens with their aluminum cousins.

Aluminum is reactive to acidic liquids, so the bottles are lined with an enamel or epoxy layer, which some scientists have linked to BPA. Yes, these bottles are lightweight and feature design-centric styles, but it’s safest to keep away from them. Stainless steel offers those same attractive features without the worry of dangerous chemicals.

Nalgene Backpacker

The brand, famous for its variety of plastic twist-top bottles, has introduced a stainless-steel option equipped with no lining and the same wide mouth to fit ice cubes or a filtration device.
Buy now: Nalgene, $29

Klean Kanteen Classic Stainless Steel Bottle

While many classic stainless steel bottles offer only a twist-off cap, Klean Kanteen provides a variety of options, including a polypropylene sport nozzle. But if you wish to stay away from all plastic, choose the full stainless-steel cap.
Buy now: Klean Kanteen, $21

Environmentally friendly water bottle options

If we take time out of our days to target certain muscle groups during a workout and prepare a meal with carefully selected ingredients, why wouldn’t we pay attention to the type of water bottle we’re hydrating our bodies with? Reusable plastic bottle manufacturers claim their containers haven’t contained BPA since 2010, but stainless steel has no need for any type of lining that could potentially leach harmful toxins.

Although stainless-steel bottles are more prone to denting when dropped, the material won’t crack like its plastic alternative. Plus, the polypropylene cap is one of the safer plastics on the market, though many bottles do have a stainless-steel cap option. So the next time you find yourself lost in a sea of water bottles, wade over to the group of stainless-steel options. Your body (and Mother Nature) will thank you.