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SAC Health Minute: "Let's Talk About Water Bottle Safety"

  • Jun 10
  • 2 min read

Let's Talk About Water Bottle Safety: Is It Safe to Drink Water Left in Your Car?


We’ve all been there: you’re running errands, getting back into your car on a warm day, and you spot a half-full water bottle sitting in the cup holder from yesterday. You’re parched, so you reach for it.


But a common question we receive at SAC Health is: Is it actually okay to drink from a water bottle that has been left inside a car overnight?


While doing this once or twice on a typical day won't usually cause severe, immediate harm, making it a habit carries two major hidden health risks. Here is what you need to know before you take that next sip.


  • Plastic Chemicals and Extreme Heat

The interior of a car acts like a greenhouse, trapping heat and causing temperatures to skyrocket quickly—even overnight or on mildly warm days.

When a typical plastic water bottle is subjected to these dramatic temperature shifts, the structure of the plastic can begin to break down. This causes chemicals like BPA (bisphenol A) and phthalates to leach directly into your drinking water.


  • Rapid Bacterial Growth

If you’ve already taken a sip from that bottle, bacteria from your mouth have traveled into the water. Your car provides a warm, dark, enclosed environment. This creates the absolute perfect breeding ground for those bacteria to multiply at an accelerated rate, especially when left to sit overnight. Drinking that same water the next day means you are introducing a massive dose of bacteria right back into your system.


Better Than Plastic and Other Tips:

You don't have to compromise on staying hydrated while on the go.

  • Switch to Better Materials: Choose high-quality stainless steel or glass bottles for your car trips. These materials won't leach harmful chemicals when the interior of your car heats up.

  • Fresh is Best: Always aim to fill up with fresh water before you leave the house.

  • The Multi-Day Rule: Never leave a half-drunk bottle of water in your car for multiple days. If you forgot it overnight, it's best to dump it out and start fresh.


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