Hard Water Spots: What are they? How did I get them? How do you remove them?

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Hard Water Spots: What are they? How did I get them? How do you remove them?


Oh those nasty looking spots!! What are they? How did they get there? And how do you get them off???

Today, we will break down a paint contaminant called a “Hard Water spot”. I’d venture to say that a good +90% of cars in Hawaii have them, they’re virtually impossible to avoid unless you know the sources in which they come from. And they are so hard to remove, you can virtually scratch your paint off and they’d still be there. Have no fear, They can be safely removed if treated quickly enough without damaging your paint, glass, or trim.’

First, What are they and where do they come from?
Basically, all of our tap water here in Hawaii is treated with minerals to make them drinkable and potable. Typical minerals found in our water are Calcium, and Magnesium, among others. And depending on the source of the water, can permanently damage your paint, glass, or trims if not treated and removed. Unfortunately, the only thing that can stop you from getting a Hard Water Spot, is to not allow treated water to dry onto your vehicle. No wax, sealant, or paint coating is impervious to these spots.


The “Spot” occurs when this treated water is allowed to evaporate on a surface, leaving behind the minerals which dry and harden into the form of the water droplet in which they started as. The strong Hawaiian sun will then “bake” these minerals and harden them making them very difficult to remove. In many cases, a Hard Water spot can form and essentially become permanent within minutes under the sun.

So, How did I get them on my car you ask? Well, There are many sources of hard water stains. Here is a list of typical sources of Hard Water Spots

1) Sprinkler Systems- If you live in an apartment complex, or park in a lot that has faulty sprinkler systems, this could be the most sever source of Hard water spotting. In the above picture on the right, you will see a vehicle that was being blasted by a faulty sprinkler system at an apartment complex. Over the course of days and weeks, this sprinkler sprayed water on the cars surface while the sun was baking it onto the paint.

2) Automated Car Wash Machines- Although many of them claim to use “Soft Water” or De-ionized water, this is one of the most common sources of hard water spotting that we encounter on a daily basis. The blowers at the end of the wash tunnel never get all the water trapped in your panel seams and jambs, and the leak out while driving and then harden. We never recommend Machine washes, but if you do I’d invest a few extra minutes to towel dry the car yourself OR pay the extra couple of dollars to have your car towel dried. Just be sure you are using clean towels so you dont scratch your paint.

3) Washing your own car- The truth is, unless you have 8 arms and can move supersonic speeds like The Flash, you’ve never going to be able to towel dry your car on your own before the water starts to evaporate. But there are some ways you can make it easier:

Wash your car early in the morning or late in the evening when the sun isn’t as strong and your vehicle is cool to the touch. If possible, wash your car in the shade!
Use a leaf blower or the blower part of your WetVac to blow dry your vehicle paying close attention to the seams in between panels.
Use a high quality microfiber to dry your vehicle, they are very absorbent and will not scratch. Water blades, shammies, or terry cloth towels are not recommended.
Keep your vehicle waxed, or even better yet, Have your vehicle coated with a Superhydrophic clear coating. Waxes, sealant, and coatings will bead water allowing it to roll off easier with the blower, and will act as a sacrificial barrier from allowing the hard water spot to set in as quickly.
Do not fill your windshield wiper fluid with tap water! Believe it or not, your dealer may even fill with tap water. I recommend buying “Windshield Washer Fluid”, they sell it by the gallon for $2-3 at Walmart or O’Reilley’s.

Ok, so now you know what they are, where they come from, and some pointers on how to avoid them. So What if you already have them on your car? What can you do, to remove them?

The Key to easy removal is to get them off while they’re fresh. The sooner you treat the hard water spots, the easier they will come off, and the less damage they can do to your paint. If you allow them to sit over time they will eventually “Etch” themselves into your paint which will require removal of some of your clear coating in order to fully remove.

There are basically 2 ways to remove Hard Water Spots, Chemically or Mechanically. There are a variety of chemical water spot removers which are sprayed on, allowed to dwell and or agitated, and then rinsed off. This is typically the easiest way, however the chemical strippers may also do damage to other surfaces such as your trim, windows, chrome, or metals, especially in the hands of inexperienced users.

The other way is to mechanically removes them, which uses micro-abrasives to abrade them off. We prefer this because we can use abrasives designed specifically for the surface we are treating, so we do not cause unexpected damage.

For any of you reading this that feel inclined enough to try removing water spots yourself, we recommend our Pearl Nano Water Spot Killer for a chemical removal, or I personally like to recommend Meguiars Ultimate Polish, or Ultimate Compound, and a microfiber applicator which can be purchased at your local auto parts store. Please read the directions thoroughly, and apply only to a clean, cool surface.

If you feel like you need professional help please do not hesitate to call us at Windward Mall.

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