Is it Safe to Keep Bottled Water in Your Trunk?

Sometimes life can feel like a symptom search on the internet. Regardless of what we do, someone always says that doing it is going to kill us. Emergency preparedness is all about being ready to handle situations that are dangerous. Lack of drinking water is decidedly a real problem. We have to prepare without panic and avoid the pitfalls of bad advice. Perfect preparation only exists in a perfect world. Even your best efforts can go amiss.  Proper storage techniques are vital because accidents and unforeseen events will happen.

Is it safe to keep bottled water in your trunk? If you’re thinking about storing water in a car trunk indefinitely, think twice. Six months is about the maximum storage time for bottled water in the car. Heat, cold, sunlight and vibration are the enemies of most sterile storage containers. Plastic can be photodegradable, which means every time you open your trunk you are helping to breakdown the plastic. Cold and freezing temperatures in winter will cause water expansion and can compromise the integrity of the bottles causing leaks. Overall, it’s not a good storage solution. 

Balancing Act

Preparedness can be a balancing act. Having nothing to drink or eat can be a serious problem. On the other hand, if you keep your BOV stocked with perishables then you’re probably throwing away money. Make no mistake, even “non-perishables” go off, thus the expiration dates. Sadly they do so faster in some locations and your trunk is one of these. Every wasted bottle is cash in the trash.

Let’s not be unnecessarily alarmist. It’s fine to transport water in your trunk. You need to find a different long term storage location that’s reasonably climate controlled. Your car trunk is just fine for storing tools, but food and water storage have different requirements. If you feel the need to store water or food in the trunk, then make certain to swap it out as often as necessary. Abide by your rotation schedule and self-enforce strictly to avoid problems.

Now the kicker. There is a way to “get away with,” improper storage, but only for water. You need to have your own water purification system in place. You can clean the same water as many times as you need to. Thus, with the right preparations, your storage issues are limited to making sure the containers don’t leak. Lost water is gone. Luckily, you can learn to purify water yourself without the overcomplicated factory setups.

Where Does it All Come From

Do you depend on your sink for drinking water? Most of us do. If you are fortunate enough to have never been without water, then you are the exception. Most people have at least had a service interruption. Water storage is a lifesaver. Yet even among people who have survived a serious event like a hurricane, basic preparedness in the USA is still inadequate.

Having some basic supplies is not enough. You should be questioning the source of your supply. Sadly, not all bottled water comes from a spring in the mountains and even when it does, that doesn’t make it safer per se. Tap water is monitored closely but private wells are not.

Is it Worth the Cost

Is bottled water safe? Well, it is water. Water is safe when it’s clean for the most part, but it’s not all handled the same way. How water is regulated depends on the source. Moreover, your bottled water may not be what you think you’re getting. It’s up to 9000 times the cost of tap water so that makes it better… right? You’re not going to like hearing this but some bottled water is tap water.

So, what are you paying for? To be honest, your money is going to a small amount of plastic and having it filled under strictly regulated conditions that should help prevent contamination. In the first place, not every company works exactly the same. There are many different additional filters that water bottling companies may use.

Professional Water Filtration

The difference between a DIY filter and the extensive system in place for bottled water is the extent and cost of the technology. Arguably, anything that gets your water clean enough to keep you from getting sick is a good filter, but the extra effort of a system like this may help preserve water longer.

  • Multimedia Filter- This can be sand or other mediums. Removing any particles that are over a micron helps keep the water moving through the later purification steps.
  • Carbon Fines Trap- Carbon filtration is incredibly effective at removing odors and flavors among other contaminants. Moving and shifting carbon can cause tiny black particles to be released into the water, so there’s a filter for that as well.
  • Tank Vent Filter- Interestingly, this filter isn’t for the water. A tank vent filter creates sterile ventilation and prevents some spoilage.
  • Resin Trap Filter- For the purpose of further reducing any filtration medium causing contamination, the resin trap filter is used.
  • Fine Particle/Bioburden Reduction Filter- Microorganisms that are still present need to be removed. Whether they are alive or dead, things like bacteria, yeast, and mold are removed.
  • Sterilizing Filter- Additional membranes are used after reverse osmosis to assure water purity.

Shelf Life

The FDA doesn’t give an expiration date for properly stored water. This means you need to follow the guidelines for keeping out contaminants. Buying pre-bottled water meets many of those specifications. If you need to bottle your own, or re-bottle water because of a broken container the process is simple.

  1. Use a plastic bottle with a screw top. You want a food safe bottle that never had any non-food inside.
  2. Wash your bottle and cap with dish soap and rinse thoroughly.
  3. Add liquid bleach (sodium hypochlorite 5.25%). 1 teaspoon per gallon of water will kill almost anything inside the container(s).
  4. Fill the container with the bleach and water solution and leave for 2 minutes.
  5. Dump and rinse well using clean potable water.
  6. Fill, seal and store.

Store your airtight water bottles in a cool but not freezing place, room temperature or preferably below. Use a dry and dark storage location and be sure to raise the containers up off the floor. Bricks or wood pallets work just fine for this.

Re-Purify Stale or Contaminated Water Easily

Unless your water has something radioactive in it you can probably get it clean again without too much effort.  Knowing your contaminants and filters is an extensive subject, but water purification can be as simple as boiling or using bleach. Furthermore, you should use a filter with activated charcoal whenever possible. Between those three basics, you can handle most water problems.


Though boiling times vary by altitude, three minutes at a rolling boil should be more than enough. Rolling boil, for those not familiar with cooking terms, means a fast and extremely hot, bubbly boiling.


When you choose the bleach method don’t forget to check for additives in the bleach. Choose one with no added scents and so forth. You’ll need household bleach which should be 5.25-8.25% chlorine. Five drops per liter or 1/4 teaspoon per gallon is plenty. Don’t overdo it.


Filters are fairly intuitive. Water goes in one end dirty, usually the top, and comes out the opposite side cleaner. Different styles exist, but building a basic multilayer filter means you need a container with some pebbles, clean sand, charcoal and a way to get the clean water out like a spigot.

Final Thoughts

Most of your body is water. Most of the planet is water. It seems like understanding the basic properties of water and the requirements for water safety should be one of the first things we learn as children. Strangely, it’s not really a priority and most people, at least in first and second world countries, don’t spend much time thinking about their water. That includes areas where drought is a problem and even desert dwellers. Only when it runs out or we have a serious contamination issue do we suddenly realize we were woefully unprepared.

Water handling is one of the most serious issues we face. Supply and demand for clean water become a bit more strained every day as the population grows and we create ever more pollution. With this in mind, we still need to avoid panic. Preparedness is inherently solution oriented.

Additional Questions

  1. Is there a better way to store water in my car? You can try storing your bottles inside a cooler for insulation. Likewise, using glass or metal bottles may help. If you are concerned about BPA’s, or other plastic leeching issues, then avoid plastics entirely. Interestingly, glass can also leech chemicals at high temperatures. The process doesn’t release the same quantity, but it does have different, wider-ranging chemicals to release.
  2. Can I drink bottled water if bubbles form inside? There’s no need for concern. You can drink the water. The bubbles are made of air that was dissolved before the bottle was sealed. Later, heat releases the oxygen and it forms those troublesome little bubbles.
  3. How long does water stay sterile? If you find yourself unable to seal a container, most water will stay safe for about 24 hours before you should boil or otherwise purify it again. Try to at least cover any exposed water. Obviously, you can drink a small amount and store it in your body. However, for larger quantities, you’ll need to find new airtight containers soon.