WHY IS THERE WATER IN MY HEADLIGHTS?

You’ve walked out to your car only to realize you have what seems like water droplets inside your headlight. Your first thought is probably along the lines of “How do I remove this fog from my headlights?” I know you’re reading this to find out why it happens and how to prevent it. First, we’ll explain condensation and how it happens in your headlight. Then, we’ll share our tips and tricks on how to remove and prevent water build-up inside those headlights.

Picture by Matt Graham from Headlight Junkies

WHY DO I GET MOISTURE INSIDE MY HEADLIGHTS?

The answer is simple, you get water in your headlights from the process of condensation. Condensation, by definition, is the conversion of a vapor or gas into a liquid. In this case, water will collect as droplets on a cool surface when humid air comes in contact with it. Most condensation takes form in variations of misting, fogging, or even small to large droplets. Condensation is a normal process and can happen especially after a change in weather. The misting within the headlight will dissipate on its own. However, if you have excess amounts of condensation then there could be an underlying issue with the headlight itself.

Photo by Shawon Razzaque of Headlight Junkies

If you have an invasion of water in your headlight, it could lead to further issues. An excess amount of water build-up might also hint at the headlight having damage, whether that’s a hairline crack in the lens or a failing seal. This water build-up could have the potential to damage the internals of your headlight, making the whole unit useless.

Headlights naturally generate heat when in use, bulbs create heat, and that heat will be transferred through the headlight housing. Because of this heat, headlights need to have a way to ventilate and regulate internal temperatures. Due to the process of thermal convection, condensation will occur when the warm air moves up, the cool air moves down, and the two meet. If there is damage to the headlight which prevents this process from happening, you will start to notice condensation that builds up heavier and forms larger water droplets.

HOW DO I CLEAR FOGGY HEADLIGHTS?

Now you know why condensation happens, but how do you remove excess amounts of water from your headlight? In most cases, you really don’t need to do anything. Depending on your local weather, the condensation might be completely normal and will disappear once the temperatures have balanced out. However, if you’re unlucky enough to be stuck with pesky moisture that won’t go away, we have a few tips on how to fix that.

• One of the first suggestions you’ll read or hear will be applying heat to the headlight. You can use a hairdryer or a heat gun to up the lenses, hoping that the condensation then dries out.
• If you don’t have a heating element, you can also try using the sun. Remove the headlight bulbs and the dust cap and park in direct sunlight to recreate the same effects from above.
• If you’re trying to combat condensation in a place without a lot of sunlight or natural heat to help, the next best solution is to keep the vehicle away from water. This includes when it rains or even taking it through a car wash. Let the headlights dry out on their own time.

These methods are an easy way to help remove water from inside your headlight. But how do you prevent water from getting there in the first place?