How Hard is Your Water, And Why Does It Matter?

by Kinetico Published 3.10.2016

What Makes Water "Hard?"


Your water is hard when it has minerals dissolved in it. Usually these minerals are a combination of Calcium and Magnesium.  An old way of describing how much hardness there is, is to use "grains per gallon."  If you have five grains per gallon (gpg) and pulled out all the minerals, that amount of hardness would be about the same size as a regular aspirin tablet.  A more modern way to describe hardness is in parts per million (ppm), or milligrams per liter (mg/L).  One grain of hardness is the same as 17.1 ppm or 17.1 mg/L.  I'll use grains per gallon because that's still the convention in North America where I live.

If your water has less than one grain of hardness, it is defined as "Soft."  Water with more than one grain of hardness is "Hard," and can be Slightly Hard (1.0-3.5 gpg), Moderately Hard (3.5-7.0 gpg), Hard (7.0-10.5 gpg), and Very Hard (above 10.5 gpg).  Water that has been treated by a water softener, reverse osmosis, or a distiller will be Soft.

Hardness is important because it prevents soap from lathering, reduces the effectiveness of detergents, and causes crusty scale because those extra minerals can't stay dissolved forever.  As a result, people with Hard water have to use more soap and detergent to get the job done, and appliances (dishwashers, water heaters, clothes washers, etc.) and fixtures (faucets, showerheads, etc.) don't last as long as they should.

How Do We Test For Hardness?


In the Laboratory, we add chemicals to the water that give it color, then add another chemical drop by drop until the color changes.  The number of drops is a very exact way to find out the number of grains of hardness in the water.  This color change test is called "titration."  There are titration test kits available for field use too, and they can be very accurate when you want to know exactly how much hardness is in the water.

In the field we often use a Soap Test to demonstrate the difference between Hard and Soft waters in a dramatic way.  There is an official soap to use, which means its concentration is the same in every bottle, year after year.  This standard soap is made so that one drop will create suds in a test tube of water if that water has less than one grain per gallon.  If the water needs two drops of soap, it should have about 2 grains of hardness, three drops for 3 grains, and so on.  You can get a kit to try this yourself (it's also a fun demonstration for school science projects) from the source listed below.  There are other soap test kits available too - some are listed below as well.  You could even try using a diluted baby shampoo or dish soap to create your own "standard" solution (it's best to dilute with Soft water; to do the tests you'll also need an eye dropper and a container like a small jar with a lid).

There is another simple test called the "Tea Test."  Hardness minerals bind with molecules found in regular tea.  Soft water will make a cup of tea that is the classic orange-brown color, and you can easily see the bottom of the cup.  The flavor of the tea should be crisp.  Hard water will make a suspension of those hardness minerals, which makes the liquid muddy and dulls the flavor.

As a Research Scientist, I have run a series of experiments to investigate claims made by manufacturers of so-called "physical water treatment" devices.  These typically rely on a fixed magnet, an electromagnet, or some unique property given to an ion exchange resin.  Among the many claims for these physical devices is that they give water all the properties of being Soft without actually removing the minerals.  The Soap Test is an easy way for anyone to check out the claim that a device will reduce how much soap is needed.  The Soap Test is considered to be fair because the test is standardized to give consistent results, it is widely available, and is reasonably accurate.  In tis case we just need to see whether the treated water really does behave like Soft water; if it takes more than a drop of the soap solution to create rich suds then the claim is busted.

Test Results


For the Soap Test experiments, I also came up with a way to mix up each test tube in exactly the same way, every time, to be as fair and scientific as possible.  Below is a photo of the results from one test, where Hard water (HW), physically treated water (PWT), and Soft water (SW) are compared.  The hardness of the HW was 20 grains per gallon.  That same Hard water was passed through the physical treatment device to provide the sample used below.  The Soft water was made by passing that Hard water through a standard ion exchange water softener.  Just one drop of soap was added to each test tube, they were shook for 3 seconds, and then the photo on the left was taken.  The softened water made suds, the Hard water and physically treated water did not.  This test shows that folks who have softened water can actually use less soap. 


Recent independent studies on the effects of softened water on appliances, clothing, detergent use, and carbon footprint, are available online.  Those links are listed below as well.

For more information

1. Water Hardness levels:

2. Soap Test Kits:

a. The one I use: 

b. Other kits:

3. Recent independent studies on the effects of softened water


By: Mark B., Senior Research Scientist




The Better Water Blog 1-Year Anniversary

by Kinetico Published 7.1.2013

Illustration of a tablet showing the blog, and a half-eaten slice of birthday cake

Time really does fly when you're having fun, doesn't it? Over the last year, we have tried to bring you posts that help you understand, value and respect life's most vital resource: water. We know some of you have been with us from the very beginning, and we're really grateful for that. But for those of you who are new to the Better Water Blog, here are some posts you could start with from this time last year.

Why are Boil Water Alerts So Important?

By Cathy J in The Science of Water

Have you ever had a Boil Water Alert (BWA) issued in your area? These public warnings can be worrisome if you've never heard them before. You may ask yourself, "Is my water really safe?" Cathy answers some common questions about BWA's in this informative first-ever Better Water Blog post.

How a Water Softener Works—Mystery Solved!

By Stuart P in Water Treatment Technology

Stuart's fascinating, lighthearted post clears up some of the mystery behind water softeners. Even if you already know all there is to know about ion exchange, water softeners, soap curds and electrons, you'll enjoy the fun, straightforward video presentation where we get to see how water softening works close-up, featuring Mr. Resin Bead! 

We All Have Our "Just In Case"...Mine Has To Do With My Drinking Water

By Keith B in Water in the News

Keith explains a few of the reasons why he and millions of others rely on reverse osmosis filtration for drinking and cooking water. "Better safe than sorry" is his philosophy as he illuminates some of the effects that fracking and PPCP's (Pharmaceuticals and Personal Care Products) might have on your water.

Do products such as magnets, electric fields or high frequency energy really work to remove hardness from water?

by Keith B Published 3.9.2013

Being a consumer today is a challenging task. We are bombarded with all sorts of product information in the media, on the web, etc. How can we make an educated decision on which product to buy or which technology to choose when there is so much conflicting information?

If we look through many of the products that are offered to the public today, there are some that, in my humble opinion, present some very questionable claims. There are a few product categories which seem to contain more than their share of these types of claims. For example, one category would be dietary supplements/OTC drugs. I am told I can lose weight, grow hair, grow certain parts of my body, enjoy life, live longer, remember more and be smarter by buying and consuming various products. I would argue that most of these probably do not work as advertised, but are not completely rejected by consumers because it really hasn’t been proven that they don’t work. We would need 25 years of data from thousands of users to prove, without a doubt, that they don’t work. One might assume the sellers understand that.

Now let’s look at our industry, the makers and sellers of Point-of-Use (POU) and Point-of-Entry (POE) water treatment products. From the time I joined this industry, 36 years ago, we have seen a few questionable products and questionable claims appear and disappear. Some have involved claims like:

1. Drinking hard water will turn your brain to stone.

2. Your health and life will benefit from “enhanced” water.

3. Various water treatment devices will give you softer skin, beautiful hair, longer lasting appliances and on top of it all, will save you money on soap and cleaners.

We know from 60 years of field results and scientifically conducted laboratory tests that ion exchange based water softeners do actually provide the benefits stated in #3. Their operation can be accurately explained using commonly accepted principles of chemistry and physics. By removing the calcium and magnesium (hardness) from the working water (the water we use to clean with) we can improve the efficiency of the cleaning and minimize the formation of harmful appliance-damaging scale. (For more information, view Stuart P's video on how a water softener works.) However, in the last few years, working water claims associated with products that supposedly modify the water’s calcium and magnesium or physical properties with magnets, electric fields or high frequency energy, or produce micro crystals of hardness that proceed harmlessly through your home have increased significantly. Unlike the dietary supplement products with their “hard to test” claims, aren’t these working water claims easy to measure?

We thought so, and for years we have been testing many of these products in our lab. In my opinion, they just don’t work; they don’t provide the promised working water benefits. If they have in some way modified the hardness, we can’t measure it, nor can we see or feel any of the proposed benefits. Other than filtering or mechanically straining suspended solids (like dirt, sand, ferric iron, etc.) with media, we have never been able to see any measurable improvements to working water produced by any technology that didn’t use ion exchange, membrane separation or chemical addition technologies.

Thumbnails of each element tested - click to see the full resolution imagesThumbnails of each element tested - click to see the full resolution images

Standard electric heating elements were exposed to hard water treated by various technologies. View Kinetico's testing results.

We are certainly not alone in doubting that these technologies are effective. A good summary of some of the literature is presented by Robillard, Sharpe and Swistock from Penn State University in their 2001 paper “Magnetic Water Treatment Devices”. Also, the WQA has issued Consumer Alerts to try and help prospective buyers of water treatment devices understand that devices utilizing technologies other than ion exchange do not soften water.

So, let’s close by looking at the following question. If some of these technologies apparently don’t work, do the manufacturers of the products using the technologies know they don’t work as advertised? If they publish data sheets describing how these technologies supposedly work, and a distributor or dealer sells the product based on those sheets, who is responsible to the homeowner who purchased the product? Interesting questions, eh?

Additional Information: WQA Magnetics Task Force Report

Contact Keith B. 

How a water softener works – mystery solved!

by Stuart P Published 6.13.2012

In the world of home appliances, there are few more mysterious than the water softener. Most other appliances give blatant clues as to what they do. A blender puts its handiwork out there for us to detect with loud noises, swirling liquid visions, and conversation-worthy tastes. The furnace heats you up, the A/C cools you down, the leaf blower, well, it moves things around. Softeners are much more subtle as they serve silently in some inconspicuous location.

Why would you ever want to buy a mysterious silent appliance that lives on a diet of salt nuggets? Many people never make the connection and so they endure the effects of hard water without ever really knowing there was a solution. They take things like bathtub ring as a natural part of life. It is actually the product of a reaction between soap and dissolved minerals in the water. The technical term is soap curd. Yes, just like in the famous poem featuring Miss Muffet. A softener exchanges the dissolved calcium ions for sodium or potassium so this reaction can’t happen.

The softener accomplishes this amazing feat through a process called ion exchange, and it follows the physical laws of electrical attraction and chemistry. Just like the opposite ends of two magnets attract each other and the similar ends repel each other, ions seek to find their proper place as they float around dissolved in water. Ions are charged particles, so some have a positive charge of varying degree, and others have a negative charge.

A classic example of ionization can be seen in table salt, also known as sodium chloride or NaCl. When dissolved in water, the sodium atoms turn into positive ions by giving up a negative electron to the surrounding water. The chlorine atoms gain an electron, and in so doing they turn into negatively charged ions.

The media inside the softener uses this principle of opposites attracting each other. It is specially made to have a chemical structure with permanently ionized docking sites to attract and hold positive ions. These docking sites start out loaded with sodium or potassium ions from the salt regeneration process. When hard water passes by on the way to your faucet, the docking sites take on the hardness ions because the attraction is stronger. The ions from the salt are released in exchange, and the result is softened water. I have uploaded a video to this blog to help explain this process—please note the accomplished actor in the video :)

View this video on Kinetico's YouTube channel

Hopefully some of the mystery is gone, and you can better understand how softening works and some of its benefits. 

Contact Stuart P.

Water: Understand it, Value it, Respect it. Learn more about life’s most vital resource.

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