Have hard water spots you can’t remove? I’ve been there. Growing up, hard water spots always made my vehicle look almost dirty after washing. Frustrating.
If you’re tired of hard water spots ruining your car wash experience, today I’ll break down a few ways to remove them, make them less noticeable, and even a few ways to prevent them altogether.
But first…make sure your tap water isn’t too hard
The map below shows the states with the highest grains per gallon (GPG) in dark blue. Keep in mind that if you live in states with heavier concentrations of minerals, there may not be much you can do to prevent hard water spots, so you may have to treat your water.
Source: Culligan Lansing
The six metro areas in the United States that are hit hardest by hard water are: Indianapolis, Las Vegas, Minneapolis, Phoenix, San Antonio, and Tampa.
1. Wash, dry, and protect your vehicle properly
There is no real ‘guaranteed’ way to prevent all water spots all the time (without treating the water itself…I’ll cover in a minute). That said, you can remove them pretty easily using a few basic products, assuming that your water isn’t too hard.
Dry your vehicle quickly
Based on my own personal experience in dealing with hard water, to prevent water spots you want to wipe down or air dry your car quickly (especially on a hot day).
Drying quickly can help reduce the chances beading will occur.
When hard water dries, it sometimes produces a powdery substance in extreme cases, so it’s always good to wipe away beads of water before this can occur.
Protect your vehicle with a wax or sealant
One of the most effective ways to prevent hard water is to use a good carnauba wax or sealant. The purpose of these products is not only to improve luster or shininess but really to protect your clear coat.
Since wax obviously repels water, you may find it easier to dry your vehicle since water will bead easier.
If water spots do form on this wax layer, they are much easier to remove as opposed to being stuck on a rough, unwaxed clear coat.
Opt for a lighter color vehicle
Okay, so not really a way to really prevent hard water spots, but a lighter color vehicle will make water spots less noticeable.
Midtone silver or pewter colors are typically the best for hiding hard water. If you don’t want to constantly worry about hard water spots, picking a more forgiving paint color can help.
So skip the black and dark blue vehicles if you’re not the detailing type!
2. Remove hard water spots
If hard water is a continuous problem, there are a few techniques you can use to remove them. Lightly acidic cleaners work best.
Okay: Acidic household products like white vinegar
White vinegar is a household product that can remove some hard water spots. Fill a spray bottle with 50/50 white vinegar and water and test a small area first.
Vinegar is slightly acidic as are citrus-based cleaners which is why they are commonly used for spot removers when diluted properly. I have seen people use diluted wheel acid, but would not recommend it. Any acid will chew through your paint’s clear coat over time.
Many detailing products sold in stores designed to remove bugs and other blemishes are somewhat acidic…but designed to use in moderation.
Good: ONR (Optimum No Rinse)
ONR is a great product to try that can also help remove water spots. Since no rinsing is required, many people use this in a bucket or spray bottle mixed together with water.
Tip: Warm water can make cleaners more effective at removing substances like hard water spots. Using warm water when washing can cause soap to dry faster, ONR acts as a softener and may work better for this specific application. Give it a try.
Good: Clay
For superficial water spots that aren’t baked into the clear coat, clay can also remove hard water spots.
Clay works great on windows since there is no superficial layer for these hard water spots to cling to. As always, be sure to use proper lubrication with clays.
Better: Basic car polish
Regular car polish is generally one of the best ways to remove severe hard water spots.
Anything abrasive like a compound or polish can soften the clear coat with repeated use. However, if etching has started, it may be your only option.
This video did a great job of explaining a few of the water spot removal techniques in greater detail:
Quick tip: It’s better to protect your vehicle with wax (to make hard water spots easier to remove) than to always use compounds or polishes. These grittier polishes are ideal to remove hard water spots from unprotected paint only.
Best: Optimum MDR Mineral Deposit Remover
This usually does a better job of removing minerals that are embedded deeper into the paint, since is formulated for exactly this purpose. It is slightly acidic, so it’s important to wear gloves. You apply it sort of like a wax, where you let it dwell on the surface for a few minutes, and wipe away.
Using a polish to smooth out any imperfections, followed by a good sealant or wax should yield you the best results when using MDR.
3. Eliminate hard water spots altogether
Even if you do have hard water, there are a couple of common ways to prevent this from happening. Testing the pH of your water for high concentrations of minerals before and after filtration can really illustrate what a difference these devices make.
Option 1: CR Spotless Portable Water System
A spotless portable water system is one of the most common ways to prevent hard water spots. This device works using a process called de-ionization, which removes charged particles that cause spotting (like salts and minerals).
Simply hook up your hose to one of these portable systems, and enjoy impurity-free water.
To learn more about these benefits and uses of purified water, check out a post I wrote: Deionized vs Distilled Water for Detailing – When to Use It!
CR Spotless DI-120
What I like
Affordable for beginners, great reviews
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This entry-level single filter (resin) system by CR Spotless is really all you need for one household.
Some people prefer to use their harder tap water to apply soap and finish the rinse process with their portable deionizer.
Option 2: Household water softening system
You may want to install a household water softener to prevent hard water spots. Softeners basically convert calcium and magnesium (which can cause more noticeable water spots), to sodium or potassium which should spot a lot less.
You may also find your glassware and shower doors look more clear!
While not as effective as de-ionization, softening systems can improve TDS levels by up to 95 percent, basically eliminating those very noticeable spots.
How hard water spots form
Hard water is a result of dirt and minerals being carried to the surface of a well. Magnesium and calcium are a couple of the most common, a result of water and limestone interacting underground.
While not harmful to your health, these minerals can make your car look very dirty.
Removing hard water spots every time you wash can be a pain, so just be sure to protect the surface of your vehicle on a regular basis to create a barrier between clean, naked paint and any harsh minerals in your water.
Prevention and/or treatment works for many people with hard water, but if these methods aren’t cutting it, definitely try a water filtration method.
One product I didn’t mention is isopropyl alcohol. You can read more about all the uses for isopropyl alcohol (rubbing alcohol) in detailing in this post. It’s a cheap way to remove hard water spots, but it will strip wax off your vehicle when washing. But it does have its place!
Hope this post helps :)
This post was updated on January 5, 2023.
I’ve been washing my own car and have had issues with car soap that doesn’t lather well or water spots forming no matter the materials or brands I’ve used, that means I must’ve been washing car with hard water. But thanks for your article, I have know to reducing the hardness of water and using soft water for washing cars.