Is It Safe to Drink Bottled Water Left in a Hot Car?

Whether rushing to the office or going on a camping trip, many of us always grab a water bottle before heading out. It’s a convenient way to hydrate while on the move, keeping us refreshed and energized. But sometimes, we forget to drink from it, unintentionally leaving it in the car. Days turn into weeks, and then before you know it, we’re reaching for that same abandoned bottle to quench our thirst. Depending on who you ask, you should never drink water left in a hot car for long. However, this research-backed article reveals the truth behind this dilemma.

What Happens When Plastic Water Bottles Get Hot?

Most plastic water bottles are made from a type of plastic called polyethylene terephthalate, or PET for short. “PET is a clear, strong, and lightweight plastic widely used for packaging foods and beverages, especially convenience-sized soft drinks, juices, and water,” says the PET Resin Association. But when plastic water bottles heat up, something interesting often occurs.

It could leach dangerous chemicals from the plastic into the water.

As the temperature rises, chemical bonds in the plastic begin to loosen up and break down, causing various chemicals to seep into the water inside the bottle. In a 2014 study, researchers exposed plastic water bottles to four weeks of intense heat at 158 degrees Fahrenheit. And guess what they found? Some antimony and bisphenol A (BPA) had leached into the water.

Antimony is used to produce plastic but can be toxic in high doses. BPA, on the other hand, is a compound used to make plastic bottles hard and shiny. However, it has been flagged as an endocrine disruptor and a possible human carcinogen (it can cause cancer).

However, the study examined sixteen different water brands and found that only one exceeded EPA regulations for BPA levels. And even then, it was in trace amounts. Furthermore, the FDA considers small amounts of BPA to be safe.

It could start a fire.

As it turns out, plastic water bottles can also be a fire hazard. According to a New York firefighter, “The water and the plastic create a magnifying effect and could essentially set upholstery on fire or a piece of plastic on fire.”

Under the right conditions, the beam of light can focus on a specific spot, like your car seat, which is often made of flammable materials, such as fabrics or certain synthetic materials. After a while, the concentrated light can generate enough heat to cause the upholstery to catch fire, leading to a potentially dangerous situation.

That’s why many experts recommend keeping plastic water bottles away from hot places like cars or garages and storing them in a cool, dark spot, far away from any heat sources.

Is it Safe to Drink Bottled Water Left in a Hot Vehicle?

Occasionally drinking from a forgotten water bottle in a hot car will likely not make you seriously ill—unless it’s been opened. Usually, the water inside an unopened bottle remains sealed and protected, minimizing the risk of bacterial contamination. However, the story changes when we consider opened bottles left in a hot space. Hot vehicles provide the ideal environment for bacteria to grow and multiply rapidly, so it’s best to toss any opened bottles left in your vehicle.

But what about the chemicals that may have migrated into the water? Well, it all depends on your levels of exposure. According to the US Food and Drug Administration (FDA), “BPA is safe at the current levels occurring in foods (less than 2.25 milligrams per pound (5 mg per kg) of body weight per day).” Essentially, the BPA amount that might leach from them is pretty low compared to carcinogen levels, as stated by the FDA.

However, the European Food Safety Authority (EFSA) established a new “tolerable daily intake” of BPA of 0.04 nanograms per kilogram of body weight per day (ng/kg bw/day). Considering that the FDA estimated that the average US resident over two years old consumes 200 ng/kg bw/day, or about 5,000 times the safe level set by the EFSA, should you be concerned?

It’s a tricky question because the FDA still recognizes BPA as a safe additive in food packaging. Yet, in 2012, the agency banned manufacturers from using BPA in baby formula cans, bottles, and sippy cups. Regardless, some emerging research suggests that—even at established “safe” levels—BPA exposure may cause or contribute to various health problems.

Possible Health Effects of Drinking Bottled Water Left in Hot Cars

Many research studies suggest that BPA exposure may have toxic health effects on humans. However, these are limited since they are primarily animal studies. It is still not well known to what extent BPA affects humans. Still, there are some concerns that BPA may be linked to the following health problems:

Type 2 diabetes: There is evidence that low exposure to BPA could contribute to insulin resistance and, therefore, type 2 diabetes.

Heart disease: Research shows that even low doses of BPA exposure can cause cardiovascular problems, including hypertension, heart attack, coronary heart disease, peripheral artery disease, and angina. Findings also suggest that this level of exposure could trigger blood pressure changes, atherosclerosis, and arrhythmia.

Fetal brain development: A 2019 study found that exposure to BPA during pregnancy—even at levels lower than the regulated ‘safe’ human exposure levels—can alter brain development and behavior at later stages.

Low birth weight: Research suggests prenatal exposure to BPA affects long-term body weight development by altering fat cells.

Breast and prostate cancer: Scientists believe that BPA’s estrogen-like behavior could increase the risk of breast cancer and other cancers in people exposed to it in the womb. Another study showed that exposure to low levels of BPA during development might make men more susceptible to prostate cancer later on. Prostate cancer is the second leading cause of cancer-related death among men in the US.

Hormonal disruption: Some experts believe BPA could act like a hormone in the body, disrupting normal hormone levels and development in fetuses, babies, and children. For example, one study found that men with higher BPA levels were 3–4 times more likely to have a low sperm concentration and low sperm count. Similarly, another study of women undergoing fertility treatments found that those with higher levels of BPA are up to two times less likely to become pregnant.

Reproductive disorders: A 2013 scientific study found that BPA exposure can affect human egg maturation. A separate review study found evidence that BPA can interfere with endocrine function involving the hypothalamus and the pituitary gland. More research suggested that this action could affect ovulation and puberty and lead to infertility.

Asthma: A new study of over 3,000 pairs of mothers and children from six European countries showed that BPA exposure in the womb might increase the risk of asthma among school-age girls. The study found that “there was a significant association between levels of BPA in mothers’ urine and asthma and wheezing for girls, but not boys.”

Bacterial Contamination Health Effects

As mentioned earlier, the heat inside a car provides the perfect breeding ground for bacteria to grow. As the temperature rises, any bacteria in the water can multiply faster, potentially reaching levels that can cause serious health problems.

According to the US Department of Health, drinking water contaminated with bacteria is linked to various adverse health issues, such as gastrointestinal issues (including nausea, headaches, fevers, fatigue, cramps, vomiting, and diarrhea), coma or even death.

“Infants, children, elderly people, and people with weakened immune systems are more likely to get sick or die from disease-causing microorganisms in drinking water,” the agency says.

Related: Deadly Bacteria Behind Melioidosis Now in the US: A Threat to Well Water Quality? | 15 Dangerous Diseases Caused by Contaminated Drinking Water

Concerned about BPA in Bottled Water? Here’s How to Minimize Your Exposure

While the FDA has not established proper guidelines for BPA in drinking water, you can take a few steps to reduce exposure to this and other toxic chemicals.

Use BPA-free alternatives. As consumer awareness grows, manufacturers increasingly offer BPA-free products to meet the demand. So, when shopping, prioritize products explicitly labeled as “BPA-free.” While not all products carry this label, some plastics with recycling codes 3 or 7 could contain BPA. Therefore, exercise caution with unmarked products and choose those identified as BPA-free.

Choose Glass or Stainless-Steel Water Bottles. Yes, bottled water tastes great and is perfect for days when you’re on the go, but the plastic doesn’t break down entirely in the environment. Instead, much of it is broken down into smaller fragments called “microplastics.” These bits of plastic have been detected in 17% of surface waters, including rivers, wastewaters, and oceans. Even our drinking water and are known to contain BPA, phthalates, and other similar chemicals. Moreover, microplastics can accumulate in the body and cause various health problems. So, consider getting a glass or stainless-steel bottle instead of plastic water bottles. These materials are free from BPA and are environmentally friendly.

Learn more: Microplastics in Drinking Water & How To Reduce Risk of Ingestion

Filter your water. Swapping plastic containers for BPA-free ones is a fantastic way to reduce BPA exposure through drinking water. However, filtering your water could be a safer, more affordable, and more reliable alternative to bottled water. Generally, filtration can eliminate microplastics, lead, copper, arsenic, and other dangerous contaminants in unfiltered tap water.

Best Water Filter to Remove Microplastics from Drinking Water

The fact that microplastics and other potentially dangerous pollutants have been detected in America’s tap water tells us that perhaps the water treatment systems at some municipal plants are not optimized to keep them out of our water.

Fortunately, Springwell offers two exceptionally reliable and highly efficient water filtration solutions that can eliminate microplastics and a host of other toxic contaminants from your drinking water.

The CF1 Whole-House Filtration System

The CF1 whole-house water filter is a high-end point-of-entry system that filters every drop of water entering your household. It is highly efficient and is equipped with some of the latest and most powerful water filtration technologies to eliminate 99.9% of contaminants from water.

The CF1 has a special sediment filter that removes impurities down to 5 microns. Most microplastics fall within this range, so as the water passes through the filter, the filter blocks those bits of plastic from entering your water supply.

The SWRO Under-Counter Reverse Osmosis Systems

The SWRO under-counter reverse osmosis systems are point-of-use systems that filter water at specific taps in your home. Typically, reverse osmosis filters can eliminate particles as small as 0.001 microns, so they are highly effective for removing microplastics.

Our 4-stage SWRO-Nickel and SWRO-Bronze reverse osmosis systems are no exceptions. Their sediment filter and carbon block filter remove contaminants down to 5 microns. Due to the filters’ RO nanofiltration membranes, they can also catch significantly smaller particles, like microplastics.

Final Thoughts

Proper hydration is vital, especially you’re on the move in warmer weather. However, it’s just as important to consider where you store your water and the quality of the water you drink. Leaving plastic water bottles in your car might not seem like a big deal; heat’s effect on plastic can change your perspective.

When exposed to heat, the chemical bonds in plastic can break and cause BPA and other chemicals to migrate into the water. Beyond that, hot cars provide an ideal environment for bacteria to thrive, potentially contaminating the water in opened bottles and causing illness if consumed.

Considering these factors, we highly recommend opting for BPA-free water bottles, particularly those made from glass or stainless steel. These materials are less prone to chemical leaching and are more environmentally friendly. Furthermore, installing a whole-house water filter or an under-counter reverse osmosis system can help remove microplastics and scores of other contaminants possibly in your water.