We all do it, but is it safe to use the same plastic water bottle over and over again?

About 1 million plastic water bottles are bought every minute, making a lot of trash that mostly ends up in landfills. Many people refill their water bottles to use them more than once. This keeps you from having to buy new bottles over and over, which saves money and reduces the amount of plastic waste.

But these bottles are made to be used only once, so some people are worried about where they can be used safely. We asked 8 experts, “Is it safe to use plastic water bottles more than once?” 75 percent of the people agreed that it was “likely.”

What are bottles of water made out of?

Different kinds of plastic are used to make plastic water bottles, but most one-time use bottles are made of PET, which stands for polyethylene terephthalate. PET is a clear, light plastic that is often used to package foods and drinks.

It is safe to use with food and drink in many places around the world, like the United States and the European Union.

Can chemicals that leak out of plastic give you cancer?

Many articles on the internet say that reusing water bottles can cause cancer because the plastic gives off chemicals that can cause cancer.

Bisphenol A, or BPA, is a chemical that a lot of people worry about. BPA could mess up the endocrine system, which could lead to problems with reproduction and metabolism. BPA isn’t used to make PET bottles, but it is in other plastics that are more rigid, like polycarbonate.

Even so, one study found very small amounts of BPA (5 ng/L) in PET-bottled water. Since this chemical wasn’t found in two other studies, this finding isn’t very clear.

For making PET, antimony is used as a catalyst, which is a different kind of chemical. When eaten, antimony is not thought to cause cancer, but it can make you throw up and have diarrhea.

In 2008, researchers looked at how much antimony had leached into commercially available bottled water. They did find that leaching happened slowly over time, but the amounts were much lower than what is considered dangerous.

Around 6 ppb is the amount of antimony that makes it dangerous (parts per billion). After three months at 22 degrees Celsius (71 degrees Fahrenheit), the concentration of antimony went from 0.195 ppb to 0.226 ppb, according to the study.

Researchers have looked at many different chemicals in bottled water, from plasticizers to metals. Antimony is just one of them. Some chemicals, like antimony, get into bottled water, according to these studies. As of right now, there is no proof that these are bad for people’s health.

Is it safe to leave your water bottle out in the sun?

Some people worry that the chemical leaching described above happens more often at higher temperatures. This means that leaving your water bottle in the car on a hot day could be dangerous.

In the 2008 study on antimony levels, it was found that at higher temperatures, there was more leaching. When water bottles were left at 60 °C (140 °F) for 176 days, it took them that long to reach 6 ppb, but it only took 1.3 days at 80 °C.

These temperatures are very high, so this is probably only a problem if you live in a very hot place and often leave your water bottle in the Sun to heat up.

How about tiny pieces of plastic?

Microplastics are pieces of plastic that are very small. They can be found almost everywhere, even in the water we drink. In fact, a study found that microplastics were in 93% of plastic water bottles that had just been opened.

The WHO looked into the possible risks of microplastics and found that, based on what they know now, they don’t pose a big risk to human health.

Dr. Umar Abdulmutalib from the University of Surrey says something interesting: “Newly made plastic bottles might have more microplastics than used ones.”

Dr. Marek Cuhra from the Institute of Marine Research in Norway agrees that drinking water from a used bottle that has been cleaned should be safer than drinking water from a brand-new bottle. His group found that water fleas grew and had more babies better in plastic tubes that had been washed with warm water than in new plastic containers.

Exist any other dangers?

Most people agree that there is one risk to reusing a disposable plastic water bottle, but it has nothing to do with chemicals.

Since these bottles aren’t made to last, they are easy to break or damage. Dr Jill Bartolotta says, “The plastic used to make bottles is very thin, so it is more likely to break because its structure is not as strong. Bacteria can live in these cracks.”

If the inside of the bottle is damp, contamination is more likely. Bacteria can grow very quickly in bottled water. One study found that when the bottle was kept at 37 °C for 48 hours, the number of colonies grew from 1 per ml to 38,000 per ml.

The takeaway:

Six of the eight experts said that it is likely safe to use plastic water bottles more than once.

Chemical leaching and microplastics are found at very low levels and are not likely to pose serious health risks unless bottles are repeatedly heated to very high temperatures.

The risk of getting sick is more likely, so if you do reuse a water bottle, make sure to wash it often.