How To Remove Hard Water Mineral Stains On Windows & Glass

Hard water stains are often confused with soap scum that doesn’t wash off. Since it is near impossible to clean off hard water staining on glass with regular cleaning methods, here's a guide to help you out.
17 November, 2022 by
How To Remove Hard Water Mineral Stains On Windows & Glass

Hard water stains are often confused with soap scum that doesn’t wash off. The easy way to tell whether the window has a mineral stain is if a regular cleaning detergent does not have any effect on it.

Hard water mineral stains on glass can appear as droplets or a general haziness and are most often found on shower screens, windows and glass pool fencing. They can appear white through to a reddish brown colour in some instances. Since it is nearly impossible to clean off hard water staining with regular cleaning methods, we’ve prepared a guide to help you remove these types of stains from windows and glass.

What you need to know

Before we get into the guide, here is some essential information that you need to know:

a. What causes hard water stains?

• Spots of water left to dry on shower screens or glass windows. Solution: Squeegee dry immediately.

• Sprinkler systems spraying hard water onto the glass. Solution: Move sprinklers.

• Hosing concrete paths where lime bounces up onto glass. Solution: Seal concrete.

• Lime leaching out of cement from buildings onto the glass. Solution: Seal concrete.

• Silica leaching out of seals onto lower sheets of glass. Solution: Not much you can do.

• Iron leaching out of metal fly screens onto the glass. Solution: Replace the screens with nylon.

• Reddish bore water stain build-up from hosing glass. Solution: Don't hose glass.

• Iron stains from the roofing. Solution: Install effective guttering.

b. How to prepare for hard water stain removal

• Always do a test or demonstration to assess the suitability and the potential success of the procedure.

• Do not try to remove hard water stains in direct sunlight or from hot glass.

• Windows should always be thoroughly cleaned before removing any stains.

c. Precautions for removing hard water stains

• Sometimes hard water stains will look severe but can be removed relatively easily. Other times the stain will look minor, but can be impossible to remove. Do not judge a hard water stain by the way it looks.

• Only use non-abrasive white scourer pads. Test the scourer first to ensure it is suitable.

• Scrubbing the stain remover in all directions is a must. In many cases a right handed person can have different success to a left handed person (and visa-versa) just because of the direction they tend to scrub in.

• Do not allow the stain-removal solution to dry or sit on the window frames. Wash immediately.

• Do not let the cleaning product dry on glass.

• Be aware of other surfaces that may come into contact with the chemical. This is particularly important for stone and metal surfaces. For example, if you are removing a hard water stain from a shower glass panel and the surrounding tiles are marble, you will need to protect them from the chemicals to prevent etching.

See, this guy knows what's up...look how much he loves clean glass.

The cleaning guide

Now that you have got all the information you need, it is time to do some cleaning.

a. What you need.

XO2® Pixie Dust water spot and hard water stain remover

White non-scratch scourer

Window cleaning kit including squeegee and washer

Rags and cloths

Gloves and personal protective equipment


Mechanical action can be helpful. On each particular job, you can first test if a hand-held slow-speed polisher/scrubber delivers better results. Ensure the paste does not dry and the process is suitable for the glass you are working on.

b. How to remove hard water mineral stains on windows and glass.

1. Prepare the equipment.

2. Clean the surface. Scrape any debris and then use a window washer and window squeegee to clean and dry.

3. Apply the hard water stain remover as a thin paste to small areas via a suitable scourer.

4. Continue to scrub that area for at least 3 minutes in different directions before washing again with the window washing solution. Scrub north and south, east and west, left and right, clockwise and anticlockwise. Trust us, on many types of glass this with make a big difference.

5. Check to see that the stain is removed or improved and repeat the procedure if necessary.

6. Do not allow the stain-removing solution to sit on window frames. Continue to wash off with water.

7. Wash area thoroughly with water.

8. For large or difficult areas of stains use a circular pad on a battery or air-operated drill.

9. Repeat the above process if necessary.

Hard water stain removal is not a perfect science. Sometimes the results may be extraordinary, and other times it may not. When it comes to mineral stain removal there is such thing as permanent damage to the glass. Sometimes hard water staining can not be removed and in these cases, it might be worth thinking about replacing the glass or calling your insurance company to see if they will cover the damage.

How to quote for the job

Hard water stain removal on shower screen glass, windows and glass pool fencing is a specialty process and can sometimes be hard work. It is not part of a normal window cleaning service. The stain removal process is often quoted as a percentage of the replacement cost of the glass.

Demonstrations are essential for contractors to understand the work required and how they should quote. It is also good for the client to see the results they can expect. If you choose to do this yourself for the first time, please understand there is a learning curve. Hard water stain removal is also very different depending on where in the country you live and work.

As a supplier of products that removes hard water stains, we do not ever guarantee any results. The possible variables (eg. glass type, glass porosity, mineral type) are too many to account for. And we suggest that you also make no guarantees to your customers without thorough pre-testing and demonstrations on more than just one part of the area to be cleaned.

In conclusion

In most cases, you can achieve great results with a high-quality glass stain remover and the right process. As you gain more experience with these methods you can expect to get even better results.

If there is no improvement after the persistent application of this procedure, the surface may be beyond repair and the replacement of the glass may be necessary. Hard water stains can be costly and that’s why regular and effective glass maintenance is so important.

We’d love to hear any tips or tricks you’ve found successful on hard water stain removal for glass and windows. Get in touch with your thoughts, ideas experiences.

Feel free to call our customer care team on 1300 123 499, if you require any help or advice on window cleaning equipment and hard water stain removal products. For more information, you can also visit XO2's glass and window cleaning chemicals online.

Happy glass cleaning!

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