Car Care / Griot's Garage / Tech

Water Spots: The Cause & Cure

water spotsWater spots take many different forms across the various surfaces on your vehicle. The two most common (and frustrating) are the spots left behind on your paint and glass. Let’s take a few minutes to talk about what causes water spots, how to remove water spots, and finally, how to prevent water spots.



Know your enemy.

What causes water spots?

Water spots are most frequently created when hard water is left on a surface – paint or glass – to dry (technically, evaporate). This can be due to not drying your car after a wash (especially if your TDS level is high – more on this later), parking your car a little too close to a sprinkler, or even from rain water that is left on the surface too long. In a best case scenario, the minerals and dirt in the water are simply left on the surface of the paint after the water has evaporated off. Things get worse if the water contains something corrosive that etches the surface as it sits, creating a “crater.” If not addressed, these craters can actually get worse over time, as water will pool in them and continue to etch the same spot.

How do I remove water spots?

Depending on the severity, there are a number of solutions for removing water spots. As always, you’ll want to begin with the least aggressive product necessary to get the job done. So, start with the basic things. Clean the surface; this can be with Car Wash, Speed Shine®, Window Cleaner, or whatever product is appropriate for the level of dirt on the surface. Often a simple cleaning will remove some of those basic water spots caused by dirt or minerals sitting on the surface.

Paint Cleaning Clay

Clay is non-abrasive.

Synthetic Clay

Cover more ground and clay faster.

If a basic cleaning doesn’t cure the problem, clay is your next level of attack. Depending on the surface, choose paint, glass, and/or wheel cleaning clays, or our surface prep mitt. These will still attack dirt and minerals, and they’ll be more effective at pulling things off the surface that have been around for awhile and bonded to it. Give a light mist of Speed Shine and gently rub the clay across the surface to pull the contaminants from the paint. This is a non-abrasive process, so extra applications are not going to hurt.

Okay, so cleaning and claying haven’t removed your water spots; you’re most likely dealing with spots that have etched into the surface. Don’t stress! A little polishing should take care of the problem. Here’s a video that will give you some tips and information on our Surface Prep Mitts.


Always wax or seal.

How do I prevent water spots?

Simply not getting our cars wet is not an option for most of us, so let’s talk about realistic ways to reduce the likelihood of water spots forming.

First, a good coat of wax or sealant on your paint is the first line of defense. Not only will this prevent most spots from occurring in the first place, it will create a barrier between the hard water and the paint. So, if a water spot does form, it will most likely be on the wax/sealant layer instead of the paint making it much, much easier to remove.


Always keep it clean.

Second, keep your car clean. I can’t stress this enough. No matter how hard we try to avoid it, rain will fall, our cars will get hit by a poorly aimed sprinkler, and unwanted water is going to end up on our vehicles. As we talked about earlier, it’s not the water that causes spotting; it’s allowing what’s in the water to sit on the surface. Keep some Spray-On Car Wash on hand and don’t delay washing your car (though, as mentioned above, staying current on your wax/sealant will slow down the “rush” of getting the car clean before spotting occurs).

Lastly, rinse with pure water. Average tap water ranges anywhere from 140-400 ppm total dissolved solids, or TDS (measured as the amount of mobile charged ions, including salts, minerals and metals, in a given volume of water). Water is considered “hard” anywhere above 170 ppm, so there’s a good chance you’re rinsing your car with hard water. You can measure this with a good TDS Meter.

Even if you’re quick with the drying towel, sometimes the minerals can be quicker. Filtering them out of your water (no need to do this during the wash… save your filter for the final rinse before drying) will prevent minerals from sitting on your paint and glass.

In-Line Water Softener.

Which water filter is right for me?

At Griot’s Garage, we offer two different water filters; our In-Line Water Softener and our Portable Water Deionizer. Both are going to be effective at filtering the water, but there are a few cost and usability differentiators.

The Portable Water Deionizer is the best, no question. It comes on a roller caddy, has easy-to-use on/off valves (to switch between tap and filtered water) and, in the long run, is the more cost effective filter.

Our In-Line Water Softener is also a great choice, and better for the user that doesn’t have overly hard water or isn’t sure he’ll be using it that often. It includes quick-release fittings on each end that allow you to install and use it without having to thread it on and off, but it will require turning the water off during install. Simple, just not as quick and easy as the Portable Water Deionizer… This is one of those “good vs. best” scenarios.

Portable Water Deionizer.

I’m a numbers guy. Let’s break down the cost difference; I’ll use a best-case 100 ppm and worst-case 400 ppm example. To give you price points, our Portable Water Deionizer runs $370.00 with each refill being $89.99. The initial cost of In-Line Water Softener is $129.99 with refills running $109.99.

With a TDS level of 100 ppm, the Portable Water Deionizer will filter 705 gallons of water before needing a refill. Filtering the same water, you can expect 198 gallons from the In-Line Water Softener. To take into account at least one refill of each, let’s look at the cost of filtering about 1,400 gallons of 100 ppm water.

Cost Comparison: Filtering about 1,400 gallons at 100 ppm.

Now, let’s assume you’ve got really hard water measuring 400ppm. In this case, you can expect the Portable Water Deionizer to filter 176 gallons before needing a refill. The In-Line Water Softener will only do 49 gallons. Again, to take into account at least one refill of each, we’ll look at the cost of filtering about 350 gallons.

Cost Comparison: Filtering about 350 gallons at 400 ppm.

So, as you can see, it is about 42% cheaper to use the Portable Water Deionizer, but only using it for a few gallons per wash (remember, it’s only needed during the final rinse), it would make sense for some people to use the In-Line System since they may not need to refill too often.

Now you’re armed with all you need to know about water spots (maybe more!). If I’ve overlooked something, you’d like some clarification, or you’ve got some water spot tips of your own, please share them in the comments!

Have fun in your garage!


  1. Nothing but Fiji water touches my car. 😛

    Is it true you need to put a coat of wax or sealant after claying?

    • Our clay is non-abrasive, so wax or sealant is NOT a necessity after using it. If I’m looking for a little extra “garage therapy” on a weekend, I will occasionally clay after a wash just to keep the surface ultra-clean.

      I think the confusion comes up because we highly recommend always claying the surface before applying wax or sealant. So, if you are going to wax or seal, clay first. But if your wax/sealant is current, you can still clay the surface to keep it clean without needing to reapply the wax/sealant.

      I hope that clears it up and doesn’t add to the confusion. 😉

      • Car care is my garage therapy, and now that I have the go ahead on claying, there’s no need to wait three months to throw on a layer of wax, I can just be claying in the interim.

        Thank you!

    • ivan linares says:

      It is always a good idea to polish the surface that has been clayed. Claying will cause some marring (haze).

  2. Chris Bullock says:

    Hi–I have an Audi A6 with metallic black paint with clear coat & unfortunately, it had to stay outside for a year before the house was built. Both the paint & glass have severe water spots that I have been unable to remove. I have used both the high strength glass polish & machine polish #1 (more than once) with an orbital buffer to no avail. I have been an avid Griot’s customer for many years & need some other direction or advice to improve (hopefully remove) the water spots. Thanks for your help!

    • Yours probably aren’t as bad as this example, but it’ll give you an idea. Our product specialist bought a Volvo V70R that had 6 years of East Coast water spots built up that you could physically feel on the paint and glass. He said it took him a good 30-45 minutes to just polish the driver’s side window using the orbital and Glass Polish.

      Your case is probably not as extreme, but patience and multiple applications of Glass Polish (make sure you’re using the Glass Polishing Pad here too, as that will make a big difference) and Machine Polish 1 will likely be the best remedy. When it comes to paint, you could look into having a professional wet sand it to speed up the process, but that’s completely up to you (and making sure you find a good pro).

      Hope this helps!

      • Chris Bullock says:

        Thanks Derek–I will keep at it & let you know.

        • Chris Bullock says:

          Hi Derek–I was wondering if you saw the “How To” section in this month’s Car & Driver? On page 28 they go through several steps on how to “polish your car like a pro” & mention some of your products (along with Mother’s & Mequiar’s). Step 5 I thought was very interesting…

          • I did see that. Waxing will help mask/hide imperfections. A glaze, like our Paint Glaze, will do an even better job hiding them, but, in the end, you’re not fixing the problem so they’ll reappear as the wax/glaze wears away. Unless you’re dealing with really old, thin paint, I always prefer polishing as it will fix the problem permanently.

  3. I recently had to have a car sit outside a few days and used a breathable car cover with a hole for an antenna. Well water was able to get in underneath on top of the hood and it sat in the sun for a day. When I removed the cover there was clouded spots burnt in to the paint. How do I remove these? A picture can be found here:


    • Have you done any cleaning or polishing yet? It’s hard to tell too much from the picture, but in my experience I’d bet a mild polish -Machine Polish 3 applied with our Random Orbital or Fine Hand Polish applied by hand- should remedy that pretty easily. Using the orbital will be quicker, but hand removal is possible but may require a couple applications.

  4. William says:

    One important thing that the article left out is the very low cost per gallon of a TDS (total dissolved solids of zero is possible and in great volume when you use reverse osmosis, scale prevention device, 5 micron and carbon filter in addition to the de-ionization (DI) only system being described. While such systems cost around $3,000 and up; if a person is going to be using for a detail shop it is much less expensive than a DI system only. Specifically $0.03 – $0.06 per gallon with a 350 TDS water quality.

  5. Dr. Dick says:

    I have detailed many cars and I find many water spots. What products should I invest in?

    • If you’re still finding spots after a detail, I’d recommending investing in polishes (along with the necessary pads and orbital) to remove those.

      For paint, our Machine Polish Collection will include all the polishes you need:

      For glass, our Glass Polishes will take care of them:

      Don’t forget to watch the videos (on the product pages) on these products, they’ll give you some added information about the product along with application techniques. Let me know if you have any more questions.

  6. Thanks a lot for posting this! I have a Toyota 4Running 1997 Limited and it’s in really good condition and want to keep it that way. This data really helps to keep the paint from looking good and not getting damaged.

  7. Chris Bullock says:

    Hi Derek–another question for you…what is the best way to remove all waxes, sealants etc from the paint surface in order to start over with your products? I was thinking if there is a product I could add to the wash process to remove any left-over wax &/or sealant before I clay-polish-wax or seal. Thanks again!

  8. Dick Fletcher says:

    Hey guys I found a really good trick you might want to try to give you a fresh start on the water spots. Instead of using soap use baking soda just sprinkle it on the car and use a really wet microfiber cloth and wash. Do one section at a time and dry as soon as your finished with a section. This will not scratch the paint but will neutralize the bond the minerals have on the paint. This also works on bug splatter pretty well to especially if you use a bounce sheet to scrub. The only down side is you will have to re wax as the baking soda will strip the wax off.

    • Interesting idea! We haven’t tried it here, but I suppose it’s a reasonable alternative… Especially if you’ve run out of clay and polish. Thank you!

  9. Good post. I learn something totally new and challenging
    on websites I stumbleupon on a daily basis. It will always be
    useful to read articles from other writers and use a little something from
    other web sites.

  10. Bob Miller says:

    I live in Yuma Arizona. The water hardness bounces between barely legal, (just under 500ppm), to upwards of 550ppm. You can buy purified water (20ppm) for $.50/5 gallons. The cost is over $1.50/gal with your cheapest option. I know drinking water is more expensive everywhere else, but it’s still not that much, if you buy the 5 gallon bottles and refill them. I’m just saying, that’s a bit excessive in my opinion.

  11. Pingback: Hard water symptoms | Total Soft Water

Leave a Reply

Your email address will not be published. Required fields are marked *