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How to Remove Hard Water Stains

Written by: James Smith

Updated: October 28, 2019

We explain how to tell if you have hard water with a simple test. We also explain how to remove hard water stains from glass and shower doors.

hard water stains

“Hard” water is water with a high mineral content, where the water has accumulated high quantities of minerals like calcium and magnesium. 

Water usually becomes this way as it seeps through the soil to the aquifer. These minerals occur naturally and are present in limestone and chalk. People who live in areas with large quantities of chalk or limestone will naturally have higher levels of minerals in their drinking water than others.  

These minerals are actually beneficial for our health, and are the base ingredient in the bottled mineral water that so many people crave. However, they bring with them their own set of problems in the household.

Hard water causes limescale to build-up in pipes and in household appliances. This reduces the efficiency and lifespan of things like water heaters.

It also leaves marks on glassware. This happens when the water evaporates and leaves behind a mineral residue. These small mineral deposits are stubborn and difficult to remove, and make surfaces look dull, rough, and dirty.

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How do you know if you have hard water?

One of the telltale signs of hard water is the very thing that makes it difficult to clean and get rid of: it doesn’t react to soap.

With soft water, soap and cleaning agents usually form a light, frothy lather that cleans surfaces. But in hard water, soap instead forms a more solid structure, usually called “soap scum.” One of the defining properties of hard water is that the ions in the water destroy the lather-producing capabilities of soap.

Another telltale sign of hard water is the presence of white, mineral residue on faucets, shower heads, and glassware. Hard water also causes a white mineral buildup around drains and inside water kettles.

Here’s a quick test to see if you have hard water:

  1. Use a clear plastic water bottle (or other clear container that has a lid) and fill it mostly with water
  2. Add 10-12 drops of a simple soap (dish soap isn’t great for this purpose, since it often has additional ingredients. Castile soap is best, or a simple liquid hand soap will work)
  3. Shake the bottle vigorously
  4. Examine the bottle. If there is lots of foam and lather on the surface, and the water itself is clear, you probably have soft water. If there is little lather, and the water is cloudy and swirling with particles, you probably have hard water

A more scientific method and one that would give you an actual hard water reading in parts per million (ppm) would be to use a test kit. These test kits are available on sites like Amazon and they are relatively inexpensive. They usually consist of some strips that change color (like pH strips). You then match the color to the chart to give a reading in ppm.

Problems with hard water

Hard water isn’t a health risk, but the deposits can build up inside pipes and drains, making them less effective. 

Hard water causes limescale which bonds to the heating fixtures and elements of appliances like water heaters and kettles. This renders them less effective and and decreases their lifespan too.

limescale build up inside a pipe
Limescale build-up in a pipe

Due to the way that hard water interacts with soap, it can make a person feel less clean after a shower, and make laundry dull and colors less bright.

Finally, those stubborn hard water stains build up on glass, tile, and windows, reducing their shine and making them look dull and dirty even when they have been cleaned.

How to remove hard water stains from glass

Hard water can create stubborn mineral stains that are hard to remove. Here’s how to get hard water stains off glass:

  • Scrub them

Make a paste of baking soda and water. Use a sponge to apply the paste and scrub in a circular motion. Using hard brushes or more abrasive ingredients can damage glass, but baking soda paste works well for smaller areas where the stains aren’t severe.

  • Soak them

For glassware and smaller items, make a bath of 50% white vinegar and 50% lemon juice and soak stained items for several hours. The acid in vinegar and lemon juice naturally breaks down the minerals in hard water and removes stains with no scrubbing.

  • Spray them

Add ammonia or white vinegar to your regular cleaning products that DO NOT contain bleach. Adding ammonia or white vinegar to your spray cleaners gives them extra power against hard water stains. 

SAFETY NOTE: Never mix ammonia and bleach together

water from faucet

How to remove hard water stains from windows and shower doors

For vertical surfaces like windows and shower doors, it is more difficult to soak them in a vinegar solution, because it just runs down the surface. Here are some ways to remove hard water stains from vertical surfaces:

  • Combine baking soda and vinegar into a paste

As we know, this mixture will foam and bubble; it can be applied while it is still bubbling, or you can wait for the reaction to calm. Using a sponge or towel, apply the paste to your windows and scrub gently.

  • Use toothpaste

It may sound strange, but white toothpaste is an effective way to clean hard water stains. If necessary, thin the toothpaste a little bit with water, then apply it to the window and let it sit for a while before gently scrubbing, and then wiping it clean.

  • Use citrus oils

Using a citrus oil like orange or lemon essential oil helps hard water stains in two ways: the acids in the citrus help to fight the mineral deposits, and the oil will help prevent later water buildup on the surface.

Get a sponge or towel damp with warm water, apply 2-3 drops of essential oil to the sponge or towel, then use it to gently scrub the surface. This may need to be repeated a few times until the stains are removed.

Preventing hard water stains

While it is possible to install water-softening devices that will help to remove minerals from the water before they ever reach your faucet, that process can be difficult and expensive, and it might be easier to simply prevent hard water stains before they begin. There are a few things you can do to get ahead of hard water stains and keep them from setting in.

  • Use a rinse agent

There are products you can put in your dishwasher that help your dishes and glassware dry smoothly, with no hard water droplets.

  • Dry hard water droplets while they are still wet

Using a towel or squeegee, clear away water droplets before they dry.

  • Use a vinegar solution

Fill a spray bottle with half vinegar and half water. Spray wet surfaces with this solution and wipe them dry regularly to prevent hard water stains from forming.

Is drinking too much water bad for you? Find out in our latest article.

We also list the world’s worst polluted rivers in this article.

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About the Author James Smith

James is the chief water geek here at His mission is to empower the consumer and allow people to take control of their health. His passion for water health is contagious, hopefully unlike your tap water!

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