Hard Water Spots On a Vehicle

Posted August 27, 2019 by Chris Blaisdell, Onsite Detail

What is the Cause of Hard Water Spots on a vehicle?

If you have ever thought it was a good idea to have your car parked next to an area that regularly gets hit by sprinklers because you think that it means a free car wash..think again! Utah has some of the worst hard water in the nation and do you know what city in Utah is one of the worst offenders? If you guessed Salt Lake City you are correct. While sprinkler water is not the only culprit, for most the vehicles we see this is the most common hard water spot producer by far.

Hard water comes from water having high levels of calcium and magnesium. The white build-up that can be seen on the end of your shower or faucet head is a good indication that you have hard water. That is the calcium that, overtime, will build up and can cause build-up damage. The areas of the hard water that become visible once it dries is the calcium. The calcium doesn’t become visible until the water dries. ‘Hard water spots’ is the common term used for those areas that become visible. If ignored or not taken care of, those areas will become harder and harder to eliminate. Especially if they are exposed to the sun for a long period of time. If it is continued to be ignored, the calcium in the water can actually etch into the paint causing possible permanent damage. If you haven’t picked it up by now, you don’t want hard water spots on your car so you will want to stop parking by the sprinklers as soon as possible. It’s not washing your car, you’re adding to the work that it will take to really wash and detail your car.

If you’re just learning that it’s bad for your clear coat/paint, you either just went and moved your car to a different spot or won’t park where sprinklers hit anymore. The water that goes through your home absorbs the calcium and magnesium minerals from the ground and then makes its way through the pipes and faucets of your home. This can especially be proven when it rains. You will notice that when it rains, the rain water will not leave severe water spots on your vehicle, unless the air is dirty or there is dust in the air while it rains.

How do you remove Hard Water Spots from a vehicle?

Now that I have taught you most of what I know about hard water and how water becomes “hard”. Now we are going to get into the removing of these stubborn hard water spots. It’s important to remember that you don’t want to compromise the integrity of the clear coat/paint. So you want to avoid using cleaning agents that aren’t safe for car paint or don’t have the proper PH balanced soap. The sad news is that it will take much more than car soap to remove hard water spots. In most hard water cases it will take using an acid cleaner. Many of the acids that are most effective will need to be handled with care. Believe it or not there actually is a hard water removal acid. When properly diluted and correctly used, it can produce some amazing results. I will give a rundown of how I most effectively use acid to remove hard water spots.

The first thing I do is spray the area with some water. Sounds redundant because water is how we got in this mess in the first place but I digress.

The second thing I do it to spray the acid on the affected area. It is wise to dilute the acid. The less the dilution, the smaller the area you should work on at a time. You DO NOT want to put yourself in a situation where you are trying to rush to get the acid off of a large area. If the acid is left on the car it can cause severe damage to the clear coat of your vehicle.

The third step is what i call the agitation step. To agitate, I do an extremely quick spray of water. Not to spray the acid off but to, what I call, activate it. 

I then quickly grab the scrub brush or wash mitt and scrub the target area. If the area is really bad I will even spray some acid on the brush or mitt to assist with the hard water removal. 

After you have given the area a good scrubbing. Give it a good water rinse. You will have to dry the area to really see how much and how well the hard water spotting was removed. You will really be able to tell if you caught it early enough if the hard water is most to all of the way gone.

If you were successful in eliminating the hard water spots, you will want to prevent it from happening again. My first piece of advice for preventing it would be to not let your car get hit by sprinklers again BUT if that’s inevitable then I would say to keep a good wax or sealant applied to the paint at all times. Many waxes won’t completely stop from hard water spots appearing but they should make any new water spots that appear much more easy to remove. Even without needing to use acid. Depending on the consistency of your vehicle getting hit and/or the severity of the calcium in the water you will want to make sure that you apply multiple coats or use a high quality wax or sealant to protect the clear coat.

How do you remove severe Hard Water Spots from a vehicle?

If you are not successful in eliminating the water spots with a water spot remover chemical it is safe to say that you weakened them enough to proceed with paint correction steps. Any of the steps in the paint correction process may contribute to removing the hard water spots. Starting with spraying hard water removing acid on the surface and giving the vehicle a good clay bar treatment. A clay bar treatment is a procedure that removes surface contaminants from the paint. Be sure to keep the work areas small, lubricated and to rinse with water regularly and dry.

If that does not work then you could be looking at paint that has actually been etched from the hard water. It is also possible that the “water spots” you see still were actually caused by acid rain or other chemicals that splashed or found their way onto your vehicle’s paint. To fix this you could be looking at a process that could involve wet sanding, compound buffing, polishing, etc. Word of advice…don’t have to get to that point. Deep hard water removal can be expensive and cause damage to the clear coat and paint. I will close with a sonet. ‘Hard water break-ith the spirit of thy automobile’. That is all my friends. If you have any questions or would like to schedule a detail service, request one here, or give us a call or text (801) 412-9274, or email. Safe Travels!