The Truth About Water Spots: What They Are, How to Remove Them, and How to Prevent Them

If you’ve ever washed your vehicle and found unsightly rings or chalky marks on the paint or glass, you’re not alone. Water spots are one of the most common and stubborn paint defects we deal with—especially on vehicles exposed to well water, agricultural environments, or sprinkler overspray.

Understanding Water Spots: Topical vs. Subtopical

Not all water spots are created equal. At AgriGloss, we classify them into two types:

1. Topical Water Spots

These are the most common. Topical water spots are mineral deposits that sit on the surface of the paint. They haven’t yet etched into the clear coat, which means they can be safely removed using:

• Acidic automotive soaps

• Dedicated mineral deposit removers

• Water spot removers

These are typically caused by:

• Hard water left to dry on the surface

• Well water or untreated tap water

• Sprinklers or overhead misting systems

  
  

2. Subtopical Water Spots (Etched-In)

These occur when mineral-rich water dries and bakes into the paint, especially under direct sunlight or high temperatures. They penetrate below the surface and often require more aggressive correction, such as:

• Heating the paint to re-expand the clear coat

• Machine polishing or compounding

• Wet sanding, in extreme cases

Subtopical spots are more commonly found on black or dark-colored vehicles, tractors, or equipment parked in open fields or near irrigation systems.

Preventing Water Spots

Here’s how to keep your paint spot-free:

✅ Use deionized (DI) water for final rinses

✅ Perform rinseless washes when possible

✅ Avoid parking near sprinklers or where water can overspray

✅ Always dry your vehicle completely—don’t let water bake in the sun