Is It Safe To Drink Bottled Water Left In A Hot Car?

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We’ve all done it: had a sip of bottled water left in the car and been disgusted to find that the water is hot. A hot car heats up water in a plastic bottle, fast, and it’s not very pleasant to drink – but is it safe?

Here, we’ve answered the question, “Is it safe to drink bottled water from a hot car?”

📌 Key Takeaways:

  • Drinking bottled water left in a hot car won’t kill you – but it’s still not considered safe.
  • In extreme heat, plastic leaches chemicals and other toxic substances into drinking water, increasing the risk of health effects including breast cancer.
  • To safely consume bottled water, don’t leave your plastic bottle in the car for longer than 12 hours, or swap single-use plastic water bottles for a reusable bottle made from glass or stainless steel.

🤔 Is Drinking Bottled Water Left In A Hot Car Safe?

Drinking bottled water left in a hot car is generally considered unsafe.

Even after a few hours, the heat will cause a plastic water bottle to break down, causing chemicals like bisphenol A (BPA), which have adverse health effects, to contaminate the water.

Hot temperatures also increase the likelihood of bacteria buildup in the water bottle.

Holding water bottle in hand while inside the car

We’ve discussed the safety concerns with drinking bottled water left in hot cars below.

🩺 Safety Concerns with Bottled Water Left in Hot Car

There are a few potential issues with drinking from water bottles that have been left in a hot car:

Risk Of Chemical Leaching

BPA, a widely-used industrial chemical, is one of the most common plastic building blocks and is used in a variety of products, including food packaging, toys, medical equipment, DVDs and CDs, and single-use plastic water bottles.

However, due to growing concerns about the health risks of BPA, many products – including single-use water bottles – are now BPA-free. These products still contain other chemicals and plastics, like phthalates, that break down and cause similar health concerns.

High temperatures in a warm car can cause plastic bottles to gradually break down, leaching these chemicals into drinking water. Single-use plastic bottles are more prone to degradation in a hot space compared to the more sturdily-built reusable bottles.

How bpa gets absorbed into your body

Potential For Bacteria Growth

There’s also a risk that bacteria might grow in opened bottles left in hot cars.

If you drink water from a single-use bottle, then leave it in a hot location, the heat applied and the bacteria in your saliva may cause bacteria to accumulate inside the bottle, posing a health risk.

📊 Factors Affecting Bottled Water Safety In A Hot Car

There are a few factors that affect the safety of bottled water in a hot car. These include:


The longer the water is left in a hot location, the more time the component chemicals in the bottle will break down. We advise against drinking water from a single-use bottle that’s been left in a hot car for more than 12 hours.


The hotter the temperature, the faster the degradation will occur. Bottles exposed to extreme heat will degrade at a faster rate than those left in mildly hot or warm environments.

unopened water bottles left in hot car

Water Quality

The quality of the water may also affect what happens when the water is exposed to heat. High-quality filtered water is less likely to become contaminated when heated compared to poorer-quality bottled tap water that contains trace amounts of harmful impurities.

Bottle Type

Finally, the type of bottle and the materials it’s made from will affect the rate of degradation, or whether degradation occurs at all. Certain plastic components in single-use bottles are the most likely to leach into water, while bottles made from BPA-free plastics, stainless steel, and glass are the least likely to contaminate water in hot locations.

🔎 How To Safely Consume Bottled Water

Wondering how you can avoid the potential health effects of drinking bottled water products? Here are a few tips for safe consumption:

  • Don’t leave bottled water in a hot car for longer than 12 hours – especially if it’s a single-use water bottle.
  • Go for a high-quality bottled water brand, not a brand that simply bottles tap water.
  • Where you can, use a glass or stainless steel bottle, which won’t leach chemicals into your water, even when stored in hot places.
  • Keep your water bottle cool by storing it in an insulated box or bag. Or, buy an insulated water bottle that does the hard work for you.

❔ Bottled Water In Hot Car: FAQ

Is it bad to leave plastic water bottles in a hot car?

Yes, it’s generally bad to leave plastic water bottles in a hot car because the heat can cause the plastic bottle material to gradually break down, causing chemicals in the plastics to leach into the water. This is especially the case for single-use plastic water bottles, which break down at a much faster rate. Plus, hot temperatures promote bacteria breeding, which could make you sick.

Is it safe to drink unopened bottled water left in a hot car?

It’s not a guarantee that drinking an unopened bottle of water left in a hot car will be safe. It doesn’t make a difference that the bottle is unopened – the heat will still speed up the plastic’s rate of degradation, causing toxic chemicals to leach into the water.

How long can you leave a water bottle in a hot car?

Ideally, don’t leave a water bottle in a hot car for more than a couple of hours. Within this time period, some chemicals may leach from the plastic into your water, but not enough to have any health effects. Don’t leave a single-use bottle of water in the car for more than 12 hours.

Does heat hurt bottled water?

Yes, heat hurts bottled water. Hot temperatures cause single-use plastics to break down. In a water bottle, this could cause chemicals and microplastics to contaminate the water.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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