Most of us probably reuse water bottles—mainly to help the environment. Plus, it’s the easiest option when we’re heading out for a walk or doing any kind of physical activity.

We often do the same with leftover flavored water after a meal. But the truth is, this habit could actually put our health at risk.

Why are we saying this? What’s the danger?

This realization has raised some serious concerns. Recent research has found that certain plastic bottles contain chemicals—like bisphenol A (BPA)—that may be harmful to our health.

Scientists from the University of Exeter and Cambridge have discovered that BPA can lead to narrowing of the arteries, which increases the risk of heart attacks and angina.

What’s more, researchers from the National Institute of Environmental Health Sciences found that BPA has estrogen-like effects, which can negatively impact the pancreas and even cause insulin resistance.

Clearly, it’s important to pay closer attention to what we use to drink from. Let’s break it down:

Pay attention to packaging

Of course, we rely on health authorities to implement the right safety measures. But when that doesn’t happen—when BPA-based bottles aren’t banned or even properly labeled—we need to take things into our own hands and check the recycling codes on the packaging.

Recycling codes to look out for

These codes indicate what type of plastic was used to make the bottle. So before choosing one, take a moment to check the label.

The lower the number, the lower the health risk.
Avoid bottles marked with the numbers 3, 7, or 10, as they typically indicate the presence of bisphenol A (BPA).

On the other hand, bottles with the numbers 1, 2, 4, or 5 are considered safer, as they’re free from expanded polystyrene, phthalates, and BPA.

Recommendations

• Avoid drinking water from a bottle that’s been left in a hot car for more than 3 days, especially if it’s been exposed to sunlight.
• Don’t reuse the same plastic bottle more than 3 times, even if you’ve washed it thoroughly.
• The safest and most reliable option is to use glass bottles, which you can refill with any kind of liquid.

Another useful tip: Never freeze plastic bottles.
Freezing them could cause the plastic to release carcinogenic dioxins into the water. This was confirmed by researchers from the Johns Hopkins Bloomberg School of Public Health.

By making smarter choices about the containers we use, we can reduce health risks without giving up convenience.