Most water bottle makers intend for their products to be single-use. But if you’re concerned about the environment, or need a container in a pinch, you’ve probably wondered if you can refill them. Whether or not this is safe depends on the plastic used.
Types of Plastic Bottles
Most water bottle packaging will display a number printed inside a triangle to show what kind of plastic it is. That number can also help you determine how safe it is to reuse.
Here are three of the most common kinds of plastics found in water bottles.
Polyethylene terephthalate (PETE or PET). If you see a “1” on your bottle, it means polyethylene terephthalate. This lightweight plastic is useful for water bottles and containers like sauce bottles, nut butter containers, and other food packaging.
High-density polyethylene (HDPE). If your bottle displays a “2,” the plastic is high-density polyethylene (HDPE). HDPE is a more sturdy, durable plastic. This makes it a good material for detergent bottles, soap bottles, and gallon-size liquid containers.
Other. “7” is the ID code for plastic materials that don’t fit under any other category. Some water bottles in this category may contain bisphenol A, otherwise known as BPA. BPA is a chemical that has been linked to disruptions in the endocrine system, which is in charge of regulating your hormones. Many people avoid products that contain BPA because of their potential impact on hormonal balance.
A common concern with reusing water bottles is chemical leaching. This is when chemicals from the plastic mix with whatever liquid you put inside. But with the right storage and type of plastic, this isn’t normally a concern with single-use plastic bottles.
Concerns with type-1 bottles (PET plastics). The FDA has declared PET plastics as safe for single and repeated use.
But when these types of plastics are kept in extremely high temperatures, there is a risk of a chemical called antimony leaching. Still, chemical leaching risks are low when you store PET bottles correctly. It’s best to keep these bottles at room temperature and out of the sun to minimize any chance of any leaching.
Concerns with type-2 plastics (HDPE plastics). If you happen across a water bottle marked with a “2,” you can reuse it as long as it’s washed well and not cracked or otherwise damaged. This type of plastic is a low risk for chemical leaching.
Concerns with type-7 plastics. Not all plastics classified as “7” have BPA, but some do. Polycarbonate bottles fall under this category. A study found that participants who drank from polycarbonate bottles for one week showed a significant increase of BPA in their urine sample.
Some bottles in this category could leach BPA. If this is something you want to avoid, you can skip polycarbonate bottles and BPA-containing plastics.
Plastic Bottles and Bacteria Growth
Plastic bottles can harbor harmful bacteria, which is why most manufacturers recommend you use them only once. In truth, bacterial growth in water bottles is a much bigger concern than chemical leaching.
Bacterial growth can happen quickly from the ordinary use of touching your mouth to your bottle. Even unfinished beverages left at room temperature can have startling bacteria growth throughout the day. It’s best to reuse plastic water bottles sparingly and wash them thoroughly because germs spread so quickly.
Additionally, wear and tear on the bottle from reuse can create cracks and scratches in the surface where more bacteria can grow. With that in mind, you might even want to skip plastic bottles and buy a reusable bottle instead.
Alternatives to Plastic Bottles
If you need to reuse a plastic water bottle, make sure to wash it properly first. Most plastic water bottles don’t make for easy cleaning, so it can be tricky. But if you must reuse one, it’s best not to skip this step.
Whether you want to reuse plastic water bottles for convenience or to help the environment, you might be better off choosing a reusable stainless-steel or glass bottle instead.
They’re easy to clean after every use, and you don’t have to worry about bacterial overgrowth or chemicals leaching into your water. On top of that, they're much better for the environment.