Have you ever drunk from a reusable water bottle left in a car, only to realize that the water is warm and stale?
A few weeks ago. I was out hiking, forgot my water bottle, and found a half-empty one in the glove compartment.
It’s okay, right? It’s just old warm water! What can go wrong?
I drank it (I was very thirsty) but immediately got paranoid and buried myself in research when I got home to find the definitive answer to the question, “can you drink water that has been sitting in a hot car?”.
The quick answer is that it is safe - but only if you're using a reusable bottle made from the right materials.
Single-use plastic is bad (in so many ways), reusable plastic is better, while reusable stainless steel and glass are the safest.
Want to know why, and what harm those disposable bottles can do?
Read on and I'll explain in full...
Contents
Single-use, disposable bottles are an environmental disaster that adds to the growing global issue of plastic waste.
The FDA recommends that still water is left in a car for no longer than two years. This drops to one year for sparkling water.
However, these time frames are based on the assumption that the car remains cool.
Living in Florida, I know that a car can very quickly become a hot space. So what happens to the water in disposable plastic bottles, then?
Well, for starters, the FDA time frames come down from one year to a maximum of two weeks. But why?
Most disposable water bottles are made from PET (you can determine what your plastic water bottle is made from by checking its recycling symbol).
PET is a practical material to use because it’s flexible, clear, and light.
It also has a relatively low melting point in comparison to other plastics, which means it can be reshaped multiple times without altering its chemical makeup.
But that low melting point (around 500 degrees Fahrenheit) becomes an issue when left in the car in the heat.
This study suggests that chemicals such as antimony and bisphenol A (BPA) are released when plastic is exposed to high temperatures.
Antimony is toxic in high doses, and BPA is likely carcinogenic.
The FDA does report that the levels of BPA present in our everyday life are unlikely to cause harm, and Cancer Research UK states that “it is safe to drink from plastic bottles,” “even where plastics are heated for hours at a time.” But why take the chance?
Another problem is disposable bottles that have been opened, drunk from, resealed, and then left in a hot car.
The water in the bottle would have been pure and sanitary from the bottling plant. However, now you’ve opened it and drank from it, you’ve potentially let traces of bacteria in. This can be a problem when left in a hot car because heat accelerates bacteria growth.
Switching to good quality plastic-free bottles has many benefits over single-use plastic water bottles. But you still need to be careful when leaving them in hot cars.
Leaving your reusable water bottle in the car for an extended period on a warm sunny day will have the same effect as leaving disposable bottles…microorganisms thrive, and chemicals leach into the water.
However, it’s now common for reusable plastic water bottles to be BPA-free. So the plastic leaches far fewer chemicals and removes a potential significant concern.
Also, the beauty of using a reusable water bottle is you’re in control of what material it’s made from. For example, stainless steel and glass reusable water bottles will leach far fewer chemicals (if any) into your water when left in the car for a long time.
Wait! What? Water is a fire hazard?!
Sort of…yeah!
On very sunny days, the sun’s rays can magnify through clear plastic or glass bottles and set the car fabric on fire.
This is rare, and you’d be very unlucky for it to happen to you. But, if you plan to store your water bottle in the car, ensure it’s out of the sun’s glare. Under a seat or in the glove compartment, for example.
When bottled and stored correctly, water has an indefinite lifespan.
The International Bottled Water Association (IBWA) advises consumers to “store bottled water at room temperature or cooler, out of direct sunlight and away from solvents and chemicals such as gasoline, paint thinners, household cleaners, and dry cleaning chemicals.”
Yes, you can leave a water bottle in the car in cold weather, and it will be safe to drink (cold doesn’t cause plastic to leach chemicals as much as heat does). However, be aware that some bottles might crack in freezing conditions (due to frozen water expansion), leading to potential spillages when it defrosts again.
Drinking from moldy or dirty water bottles is not advised for several reasons.
The WHO does not identify the temperature of water in a car as a cause of adverse health effects. However, they recommend washing your hands and using good personal hygiene practices with all drinking water to reduce the risk of illness.
They also state that “further studies are needed” on BPA and other chemicals found in plastic bottles.
So, if you ever ask yourself, “can I drink water left in my hot car?” the answer is yes, it should be fine for most people, just don’t do it all the time.
Disposable bottles degrade in a hot car and should be avoided whenever possible (you should avoid them anyway due to their negative impact on the environment).
Do something good for your health (and the environment) and invest in a refillable bottle. They’re easy to clean and will keep your water fresher for longer if you leave it in a hot car (the component chemicals will break down much slower if you ditch the single-use plastic).
Ultimately, if you occasionally drink old/warm water from a water bottle left in the car, it’s unlikely to harm you. However, it’s not the best habit to get into.
Do you consider drinking water from a hot car safe? Has doing so ever made you feel ill? Do you drink from a plastic water bottle?
Or are you worried about toxic substances and prefer something else (glass, stainless steel, etc.)? Drop me a line and let me know.
