Do Emergency Flares Work Underwater? Are Road Flares Waterproof?

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By Bear

If you’ve ever had a roadside emergency, you know how helpful your flares can be. The problem is, you never know when you’ll need them. Sure, it may be a balmy, dry summer night – but what if you find yourself with a flat tire in the middle of a downpour? Will your road flare work? Can you use an emergency flare on the road? Are they the even same thing?

Do emergency flares work underwater – and are road flares waterproof?  Emergency flares do work underwater; it is actually part of the testing they go through to make sure they are effective.  However, they only work when held vertically in the water.  Now, most road flares are waterproof. You just have to pay attention to the type you buy.  It should be pretty obvious on the box whether they are waterproof or not. 


Often times, road flares and emergency flares will be used interchangeably. However, they are not quite the same thing. When using an emergency flare, you are using an incendiary type flare that creates heat and emits smoke as well as a bright flame.  When talking about a road flare, you will find large rechargeable lights that are brighter than most flashlights. You are not supposed to use incendiary flares on the road due to the increased fire risk around cars and roadside brush. 

Why Do You Need Waterproof Flares?

Emergency Flares

When talking about emergency flares, you have two options, 

  • Incendiary stick that can be lit by striking the ground
  • Flare gun that shoots light up into the air and can be seen from farther away.

You would really only need these in extreme circumstances. Often times, civilians only keep these on hand when preparing for hikes or boat trips in case of situations where they are lost and need to signal to someone. However, they are more commonly used for maritime training or distress signals.

The reality is if you are in an emergency situation and your flare isn’t waterproof, you can’t count on it helping you in rain, snow, or boating situations.  When you need to use a flare, you need to know it will work no matter what. 

Road Flares

Road flares, on the other hand, are usually not incendiary. You would only see incendiary flares on a road scene in a few situations,

  • Extreme emergency during the daytime, since regular flares wouldn’t emit enough light
  • Cops or emergency personnel would use these to cause other drivers to be over-cautious due to the extreme nature of the emergency
  • If flares were absolutely necessary and incendiary flares were the only option

It’s imperative for road flares to be waterproof due to the myriad of conditions you will experience when driving or using flares for roadside incidents.  If your car leaks water into your trunk (or wherever you store your flares), the nature of the flares being waterproof will help protect them from being damaged.  

Otherwise, the next time you go to use them, they won’t work, and you will not have a safe way to alert others to your car in extreme conditions. 

How Do Incendiary Flares Work?

Incendiary flares work by using the science of combustion of pyrotechnic materials. The ingredients vary depending on brand and type, but in a general sense, most flares work the same.

Whatever method you are supposed to use to create force (trigger on a flare gun or hitting the flare on something hard) causes a chemical reaction between a fuel compound and one of the following materials,

  • Charcoal
  • Sawdust
  • Magnesium
  • Sulfur
  • Aluminum.

Once the force is created, and the chemical reaction happens, this is when the flame appears that causes your flare to be exactly what it is supposed to be, a flare.

Proper Storage of Incendiary Flares

When you are storing incendiary flares, there are certain procedures or rules you need to follow and be mindful of. Following these recommendations will help your flares work to the best of their ability when and if you need them. 

  • Pay attention to the expiration dates.
    • Every single time you leave for whatever you have flares for, you need to check the expiration dates.  Yes, every single time.  While we can ignore expiration dates on somethings, flares can lose the ability to ignite if they are out of date.  Rendering them useless when you may need them. 
  • Store your flares properly.
    • Due to the nature of flares, being flammable, and their ability to ignite, they need to be store with the most careful intentionality. While most are waterproof, it is still recommended that you keep your flares in a waterproof container.  However, they still need to be easily accessible in case of an emergency.  They also need to be kept away from heat or fire so as not to accidentally ignite them. 
  • Know exactly how to use your flare.
    • When purchasing your flares, do plenty of research and maybe use one flare as a test subject to make sure you know exactly how to use them. You do not want to be caught in an emergency and have to figure out how to use your flares. 
  • Know the laws and requirements of where you are traveling to.
    • Some places do not allow you to carry incendiary flares, while others require that you have a certain type.  It’s always best to research and know exactly what you need for the area you will be visiting. 

Proper Storage of Road Flares

While road flares are much easier to store and manage, there are still a few things you need to be mindful of when storing and using them. 

  • Always check the charge on your flares.
    • While road flares don’t expire, they can lose their charge if they have been sitting for a while.  Before you go out, always check the charge on your flares to make sure they can be used if needed. 
  • Know the laws of using road flares where you are going.
    • Some places only allow road flares in certain instances. Other places have strict rules about how long they can be on the road…etc.  While you may not need to know this every time you travel, it is better to be prepared in case of an emergency. 

Types of Incendiary Emergency Flares

There are generally three different types of incendiary emergency flares. Each one has specific abilities that are made for different types of emergencies. 

  • Handheld Flares
    • This is held by the user and burns bright and fast. This is the easiest to carry and store.
  • Parachute Flare
    • This is a large flare and is supposed to be fired downwind.  A parachute flare is designed to find the wind and will burst above your head and float down to the ground. This allows for longer visibility before the flare disappears. 
  • Smoke Flares
    • These flares usually look like a food can and have a top you peel back. You would drop this flare into the water to help those who are following your trip or looking for your lost vessel.  They emit heavy orange smoke and have a high visibility time. 

Types of Road Flares

There are two types of road flares, each one is used in the same manner, but one if preferred over the other. 

  • Rechargeable light-up flare
    • As the name suggests, this fare is rechargeable and emits a battery-powered light that can be seen by other cars, even without lights. 
  • Reflective road flare
    • This type of flare is usually triangle-shaped and simply has reflective material on it.  When the lights of a car hit it, it reflects the light, and only then are the cars able to see the flares. 

There are plenty of options with flares that you can research and choose from when figuring out exactly what you need for your preparedness kit. The best thing you can do is always to be over-prepared and ready for any emergency you could experience.

Flares are a great way to signal when you need help and knowing how they work, what conditions they have to be kept under, and what they do is just another thing to help prepare you for an emergency. 

About the author
The most amazing writer we have, Bear is the man!