About Water Spots

by Morgan Adams

Rain, sprinklers and splashes from puddles can all ruin your car's pristine shine. The spot or stain left on your car is from the minerals remaining after the water has evaporated, not the water itself. The amount of sodium in the water also affects the severity of water spots. In general, quick drying or wiping of water from your car is the best way to avoid water spots.

Time Frame

Though not a harmful substance, water can damage car paint and windows if left on your car for an extended period of time. Time becomes a problem if water droplets are left on a car, then baked by the sun, leaving only the minerals to stain your paint. Repeated staining and evaporation can bake the minerals into the paint, requiring extensive detailing or even re-painting to remove.


Hard water has a high mineral content, while soft water has a lower mineral content. Hard water spots are the most damaging, as more minerals remain on the car once the water evaporates. Water quality is diverse depending on the area where you live and what minerals or other substances are found in that water. The southwestern United States, specifically streams in Texas, New Mexico, Kansas, Arizona, and southern California, are considered to have the hardest water. Even in the desert water spots can be a problem by parking next to a sprinkler or regularly using automatic wipers on the windshield. The hardest water in other parts of the world include Saskatchewan and Manitoba, Canada, Adelaide, Australia and eastern England.


Hard water is not considered a health risk, but it is troublesome. Water attracts impurities easily, and when combined with carbon dioxide from the air it attracts even faster. Water naturally picks up small amounts of minerals as it runs over soil and rock. The effect is a slow erosion of your car paint and scratching of window surfaces. When water evaporates it leaves the minerals picked up along the way. Surface tension causes the water to form into the smallest possible surface as droplets. The droplets then evaporate leaving what looks like spots on the hood of your car.


Many online sites recommend using wax on your car, as well as window wax on your windshield, to help water slide off the car instead of sticking to the surface. In fact, wax or polish can have the opposite effect on your car. A smooth surface increases the surface tension, forcing water beads to be tighter and taller (rather than wider). The effect is to have a higher concentration of mineral deposits in a smaller area, which can cause greater damage to your car.


Fast drying or removal of water spots is the best way to keep them from damaging your car. Many car owners regularly wash or detail their car to ensure water spots are removed in a timely manner. Allowing water droplets to stay and bake onto the paint will cause problems later. Once baked on, an acid is required to remove the spot. Vinegar is the best acid for removing water spots from car paint. To use the vinegar, first wash your car normally, then sponge the distilled vinegar one section at a time. Allow it to sit for 30 to 60 seconds and then rinse with water. Dry immediately to avoid further water spots. Vinegar does remove car wax, so that should be re-applied if desired. If water spots have sat for more than a week a polish may be required to repair etching in the paint. Of course, car washes and detailers offer water spot removal as well.

About the Author

Based in southern California, Morgan is a full-time financial analyst. She has been writing since 1995, including articles for "Wet Set Gazette" and "The American Encyclopedia of Novels". She has been writing for eHow since 2008. She holds a Bachelor of Arts from the University of Southern California and a Master of Business Arts from Cal State Dominguez Hills.

More Articles

Photo Credits

  • photo_camera Wikimedia Commons (Public Domain)