Is It Safe to Reuse Plastic Water Bottles?

Medically Reviewed by Zilpah Sheikh, MD on January 23, 2024
Written by Lori M. King, PhD
8 min read

Plastics are made from oil or natural gas, which are made of molecules called hydrocarbons. When you heat hydrocarbons to very high temperatures, they break down into smaller molecules called monomers. There are many types of hydrocarbon monomers, such as methane, ethane, propane, and butane. 

To make plastic, monomers are joined together to make a larger molecule called a polymer. The different types of plastic polymers are made of different combinations of monomers. These polymers are formed into pellets, powders, flakes, or liquids, which are the raw plastic material.

At the bottling factory, the raw plastic is put into a machine that heats it to a high temperature so that it becomes a liquid. The liquid is then injected into a bottle-shaped mold where it hardens.

There are two groups of polymers: thermoset and thermoplastics. Thermoset plastics are made of polymers made with chemical bonds that can’t be reversed. Once these plastics are molded, they can’t be broken down. Bakelite is an example of thermoset plastic. Because they can't be broken down, thermoset plastics aren't recyclable. 

Thermoplastics, on the other hand, can be melted and remolded into newer materials. Items made from thermoplastics can potentially be recycled. There are several types of thermoplastics, such as polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene, polyethylene terephthalate (PET), and polycarbonate.  Water bottles are generally made of thermoplastics.

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 type of plastic your water bottle is made of.

Plastics are labeled with a Resin Identifying Code (RIC), usually molded or printed in raised type on the bottom of the item. RIC labels are usually a number from "1" to "7" printed inside either a solid triangle or one made from arrows. Below the triangle, you will also see the abbreviation for the plastic resin type. Unfortunately, these RIC labels only tell you what plastic the package is made from and not whether or not the bottle can be recycled or reused. However, water bottles are usually made from three types of thermoplastics that can be recycled:

Polyethylene terephthalate (PET). Bottles made from PET are labeled with an RIC of "1." PET is a strong, light plastic often used for water, food, and carbonated beverages, like soda.‌ Unlike other plastics, PET is fully recyclable, although only about 30% of it is actually recycled.

High-density polyethylene (HDPE). Bottles made from HDPE are labeled with a “2.” HDPE is a sturdy, durable plastic, which makes it a good material for detergent bottles, soap bottles, and gallon-sized liquid containers. Milk jugs are often made from HDPE, and most centers can recycle this type of plastic.  

Other. Plastics with an RIC of "7" don’t fit under any other category and they're generally not recyclable. Examples include polycarbonate sports bottles, such as Nalgene. 

Which water bottles are recyclable?

Water bottles labeled with an RIC of "1" or "2" are generally recyclable. To make sure your plastic is actually recycled, don't put plastics in your bin unless they're labeled with a "1" or "2." Also, make sure you empty and rinse your bottles before you put them in the bin. While some recycling centers clean plastic before recycling it, most will toss batches that include dirty plastic in the garbage. This is because they need to avoid introducing contaminants into their recycled plastic and it may be too expensive to sort and clean them once they reach the recycling center. 

Call your recycling center to ask what types of plastic it takes. Some centers may also be able to recycle polypropylene (RIC "5"), which is what yogurt containers are often made from.

A common concern for people who reuse water bottles is chemical leaching. This is when chemicals from the plastic are dissolved into and mix with whatever liquid is inside the bottle. Chemical leaching may happen because of exposure to high temperatures or sunlight or long storage times. Some of the chemicals that have been reported to leach from water bottles include antimony, bisphenol A, and phthalates. 

Antimony is a chemical that's often used when PET plastic is made. Agencies for several governments, including the U.S. Environmental Protection Agency (EPA), regulate antimony as a contaminant in drinking water. For instance, the EPA says municipal drinking water (tap water) is safe if the amount of antimony it contains is less than 6 parts per billion (6 micrograms/liter). This amount is called the maximum contaminant level (MCL). In the short term, antimony exposure greater than this can lead to nausea, vomiting, and diarrhea. And long-term exposure can lead to increased cholesterol and blood sugar levels. 

When PET plastics are kept in high temperatures, there is a risk of antimony leaching, but the risk of chemical leaching is low when you store PET bottles at room temperature indoors. It’s best to keep these bottles out of the sun to minimize any chance of leaching.‌

Bisphenol A (BPA) is a chemical that's used when polycarbonate plastic (RIC of "7" and sometimes "3") is made. Polycarbonate plastic is used to make water bottles (like Nalgene), shatterproof windows, eyeglasses, and epoxy resins that coat some metal food cans and water supply pipes. BPA may leach into foods and liquids in polycarbonate containers. This is worrying to some people because studies suggest a link between BPA exposure and increased blood pressure, type 2 diabetes, and heart disease. It may also have possible health effects on the brains and prostate glands of fetuses, infants, and children. About 10 years ago, the FDA said that BPA cannot be used in baby bottles, sippy cups, or epoxy resins used in packaging for infant formula.

Phthalates (pronounced THAL-ates) are chemicals that are used to make soft, flexible plastics such as PVC (vinyl) food packaging, shower curtains, toys, IV tubes, and fragrances that are used in beauty and skin care products. Studies show that phthalates may interfere with normal growth and brain development in kids and increase allergies.

If you're concerned about BPA and phthalates exposure, you can:

  • Use products that are labeled BPA-free and avoid vinyl products.
  • Avoid plastics labeled with an RIC of "3," "6," or "7."
  • Avoid putting plastic containers in the microwave or dishwasher because the heat may break them down and release BPA into your foods or liquids.
  • Use glass, porcelain, or stainless-steel containers instead of plastic for hot foods and liquids.
  • Avoid canned foods that may have BPA in the epoxy resin that coats the can.
  • Use beauty and skin care products that are phthalate and fragrance-free.

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.‌ 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.

Bacterial growth can happen quickly just from the ordinary use of drinking out of the bottle. Even unfinished beverages left at room temperature can have a lot of 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 glass or stainless-steel bottle instead.

If you want to recycle your plastic bottles, first make sure they are clean. Then, put them in your designated blue recycling bin, which holds all your plastic materials, including water bottles. Place the bin curbside before the scheduled pick-up time in your area.

You can also drop off water bottles at specific locations. Check with your municipal office about designated drop-off locations in your area. Some states will have additional conditions before accepting water bottles for recycling. For example:

  • While some states accept bottle caps only when they’re screwed on tightly to bottles, others ask you to place the bottles and caps separately in the blue bin.
  • Certain states don’t accept bottles that were used to store automotive products and dangerous materials like motor oil and pesticides.
  • If some of the items in your waste lot are biodegradable, certain states ask that you not include them in the blue bin and instead choose other forms of recycling.

 

If you have plastic bottles that you can't recycle, you don't have to just toss them in the trash. You can also reuse them. 

Here are a few creative ideas for reusing plastic bottles:

  • Cut the top off plastic water bottles to make cups for pens, pencils, and craft supplies.
  • Use coffee creamer bottles to store snacks, sugar, and salt.
  • Cut the top off 2-liter bottles and paint them to make planters for houseplants or herbs.
  • Punch holes in the top of laundry detergent bottles to make a watering can.
  • Cut the handle and side off a milk jug to make a pet pooper scooper or garden trowel.
  • Make a piggy bank out of old plastic bottles.

According to the EPA, only about 9% of all plastic waste is recycled. Consumer plastics — such as soda bottles, water bottles, and milk jugs — have a slightly better rate of recycling at 30%, but there’s still far more we can do.

Some of the challenges of recycling plastic include:

  • Non-recyclable materials that end up in recycling bins, which contaminates the batch and could mess up recycling machines. This may happen when people don't know what can be recycled so they throw all their plastic in the recycle bin.

  • The price of "virgin" plastic may be lower than the price of recycled plastic, so manufacturers choose virgin plastic to save costs.

  • Some cities or towns don't have the resources or government support to provide municipal recycling services.

  • Many workers don't want to work in the recycling industry because it can expose you to chemicals and powerful machines.

To help improve the rate of recycling, buy products that are made of recycled materials, choose alternates to plastic whenever possible, make sure you know what can go in your recycling bin, and try to reuse plastic as much as possible to keep it from going into landfills.

‌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.