How to clean plastic shower doors with hard water stains

Got stubborn hard water stains on your shower glass doors that will not budge no matter what you try? You’re not alone. I’ve heard from countless readers who say they’ve tried every glass door cleaner from my magic soap scum cleaner to cleaning vinegar, hydrogen peroxide, oven cleaner, muriatic acid, steel wool, Bar Keepers Friend, Bon Ami, and other expensive chemicals to get rid of the horrid, ugly, hard water stains and white haze.

Severe situations

While most of the time, our magic Soap Scum Cleaner takes care of the problem of stubborn hard water stain, even it cannot touch a severe situation where the hard water minerals have become so embedded the surface of the glass has become permanently etched.

• MORE: How to Make Ugly Soap Scum, Mildew, and Water Marks Disappear Like Magic

Some readers report that it took multiple cleanings with the “magic stuff” to clean their glass doors. Others report they’ve tried everything from “magic stuff” to cleaning vinegar, hydrogen peroxide, oven cleaner, muriatic acid, steel wool, Bar Keepers Friend, Bon Ami, and even razor blades to scrape away the problem—all without success.

I have to admit this left me in a quandary coming this close to advising new doors to be the only solution for hard water stain.

Miracle solution

Then I discovered the solution: Sandpaper. Yes, you read that right but don’t stop reading yet. This is not ordinary sandpaper.

I’m talking about an automotive quality waterproof sanding wet/dry paper with such a fine grit, it is used in the automotive industry to polish the surface of a car to a mirror finish. You can use the same type of sandpaper to sand away the mineral buildup that has etched your shower door and return it to its original clear, clean, sparkling self.

While sandpaper is readily available in any home improvement store, please be careful when selecting. You want quality automotive wet/dry sandpaper.

The best product I’ve found for this job is Wet/Dry Premium Waterproof Sheets. This is a 12-sheet assortment of finish sanding paper ranging from #1500 to #7000 grit. The grit on this type of sanding paper is so fine it will not scratch the glass, the way that woodworker’s sandpaper, steel wool, or other abrasive products might.

Let me be clear:  What follows is for severe hard water stains. This is not a quick and easy task, but rather a last-resort solution.

Step 1: Start with #3000

For severe watermark stains, start with a piece of #3000 grit paper (cut it to a size that feels comfortable in your hand as you are going to scrub the glass with it).

Wet both the glass surface and the sanding paper with water to provide a lubricant. Do not attempt to do this completely dry.

Using a circular motion, scrub the entire surface of the glass. You will immediately begin to cut through those stubborn deposits.

Step 2: Move up to #5000

Next, move up to #5000. Repeat as above, making sure the sandpaper and the glass are wet.

Step 3: Finish with #7000

Move to #7000, repeating as needed to remove even the tiniest micro scratches that may have been left behind.

At this point, you will be polishing the surface to that mirror finish, with what feels like a piece of paper—that’s how fine #7000 grit is.

Depending on the severity of the problem, the entire process could take five minutes to much longer to finally achieve your success level. But know that it will work. Your shower doors will look like new—no fumes or expensive chemicals.

Maintenance

To keep your glass shower doors looking beautiful, get a cheap shower squeegee or use a microfiber cloth to wipe the shower surfaces (walls and doors) to remove all standing water after every use.

First published: 9-27-18; Updated & Republished 10-8-22

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