How to Choose the Right Water Test Kit for Hardness

How to Choose the Right Water Test Kit for Hardness

Water hardness is a measure of the calcium and magnesium content in water. It can cause problems with appliances, such as dishwashers and washing machines, and can also affect the taste and appearance of water. If you are experiencing any of these issues, it might be time to test your water for hardness.

Unsure of which water hardness test kit is right for you?

We can help! This guide will walk you through the different types of kits and how to choose the one that’s best for your needs. Plus, we’ll explain how accurate each type of kit is and how often you should test your water.

You’ll know exactly what to do when you get your results and whether or not it matters where your water comes from. Hardness testing doesn’t have to be difficult, and this article makes it easy to understand.

Continue reading to learn more about water hardness test kits and which one is right for you.

What is Hardness

Hard Water Film

Water hardness is the amount of calcium and magnesium in your water. These minerals can come from a variety of sources, including rocks and soil. When water comes into contact with these sources, the minerals are dissolved into the water.

Hard water is simply water with high concentrations of calcium and magnesium. It creates problems such as:

  • scale buildup in appliances and plumbing
  • deposits on plumbing fixtures
  • poor lathering of soap
  • dull and dingy laundry
  • dry skin
  • brittle hair

Calcium and magnesium

Calcium and magnesium are essential nutrients for the human body. However, too much of these minerals in your water can cause problems with appliances and plumbing, as well as affect the taste and appearance of your water.

Water readily dissolves calcium and magnesium, so in areas with a lot of these minerals in the soil, the water will be hard.

The hardness of water varies across the United States. As you can see from the map, water hardness varies significantly from region to region. In general, water in the central United States is harder than water in the east and west.

Water Hardness Map of United States
The U.S. Geological Survey has published a map of the water hardness throughout the United States

Units of measure for hardness

Hardness is measured in either grains per gallon (GPG) or milligrams per liter (mg/L). The higher the concentration of calcium and magnesium, the harder the water.

Grains per gallon is equal to 1 grain of calcium carbonate in one gallon of water. A grain is equivalent to 1/7000th of a pound or 64.8 milligrams.

Milligrams per liter, also known as parts per million (ppm), is the number of milligrams of a substance in a liter of solution. You can convert grains per gallon to milligrams per liter by multiplying it by 17.12.

Types of Water Hardness Test Kits

If you have hard water, the first step in dealing with it is to know how hard it is. You can find out the hardness of your water by testing it with a water hardness test kit. These kits use different methods to measure the amount of calcium and magnesium in your water.

There are several options when deciding how to test your water’s hardness.

1 – Test strips

Test Strips for hardness

Test strips are a common and convenient option for testing your water’s hardness. You simply dip the strip in your water. The reagent changes color to indicate the hardness of your water. This test method is very convenient and relatively fast.

One issue with test strips is that they may not always give you accurate results. If you test the same sample of water with two strips, you might get two different results. The test also depends on your ability to compare the color of a strip with the color chart to get the value.

Another issue with this method is it only gives you a range of hardness, not an exact value. For example, the color chart that comes with the Bartovation brand of test strips has five ranges:

  1. 0 grains
  2. 3 grains
  3. 7 grains
  4. 15 grains
  5. 30 grains

This means that the results will be the same if your water’s hardness is 7 or 14.9 grains.

Despite these limitations, this is a very simple, convenient, and relatively fast way to test your water.

2 – Discs

Disk test kit for hardness

Discs work in a similar way as strips, but they tend to be more reliable and accurate. The test kit includes a disk with a compartment filled with a reagent. You add a drop of water to the compartment, and the reagent changes color to indicate the hardness.

Test kits that use discs are more expensive than test strips. They are also much more accurate. This is because the ratio between the water being tested and the reagents is precisely controlled.

There are fewer options available if you want to use a disc test kit, so you’ll have to do some research to find one that’s right for you.

3 – Titration kits

Titration test kit for hardness

Titration kits are the most accurate way to test the hardness of your water. This method uses a drop-count titration.

These kits require more time and effort than test strips and disks. You also have to carefully read and follow the instructions.

To use a titration kit, you first add the required volume of your water to a test tube or cup. Then you add one drop of reagent to the sample and stir or shake it. If it changes color, then you’re done and calculate the concentration. If it doesn’t change color, you add another drop and see what happens. You continue doing this until the sample changes color.

The number of drops you’ve added tells you the hardness of your water in grains per gallon (GPG).

Titration kits are more expensive than other options and require a fair amount of skill. But they also give very accurate results.

4 – Digital meters

water hardness meter

Another way to measure hardness in water is to use a hand-held digital meter. This way of testing your water is extremely convenient because you simply insert the meter’s probe into the water sample, and it provides a digital readout of the concentration.

Some digital readers display results on an LCD screen and can measure temperature, total dissolved solids, and electrical conductivity. One thing to note with an electronic testing device – they do not test for specific contaminants like hardness. Instead, they measure another property such as conductivity and then convert that to the equivalent hardness.

The cost of a digital meter varies depending on the quality, brand, and how it measures hardness. Prices range from as low as $13 to as much as $1,450. A typical water hardness meter should cost about $40.

Most water hardness meters measure conductivity. This is because hardness is caused by minerals dissolved in water, and these minerals are able to conduct electricity. The more minerals there are in the water, the higher the conductivity.

If you’re looking for a digital meter that measures hardness, make sure it’s calibrated for hardness specifically. This way, you’ll know that the results you’re getting are accurate.

5 – Soap test

Soap test method for hardness

One of the easiest and cheapest ways to measure hardness in water is the soap test. You can use any kind of soap for this test, but dishwashing liquid works best.

To do the test, add a few drops of dishwashing liquid to a plastic bottle filled with water. Put the cap on and shake it for about one minute.

If the water forms bubbles and gets foamy, then it’s soft. If there are no bubbles or the water turns cloudy, then it’s hard.

The soap test is a quick and easy way to test your water, and it doesn’t really cost anything to do. However, it’s not very accurate and it only tells you if your water is hard or soft.

Testing Accuracy

Whenever you test your water, it’s important to make sure that the results are accurate. This way, you’ll know what kind of treatment your water needs, if any.

There are a few things that can affect the accuracy of your test results:

  • The type of kit you’re using
  • How old the testing kit is
  • Whether or not the kit has been stored properly
  • How well you followed the instructions

Most test kits will report the accuracy on the datasheet. Look for terms like “range” or “sensitivity”.

Many kits tell you the smallest amount of hardness it can detect – either grains per gallon or milligrams per liter. They also tell you how close the measured value is to the actual value. This is usually reported as +/- (plus or minus).

For example, a titration kit for hardness I use says it has a range of 0-200 ppm and an accuracy of +/-4 ppm. This means that if it indicates the hardness of my water is 100 ppm, the actual value could be between 96 and 104 ppm.

Here is the math in case you’re interested.

100 ppm – 4 ppm = 96 ppm

100 ppm + 4 ppm = 104 ppm

Frequency of Testing

One question many homeowners have is “How often should I test my water?”

Many people don’t know that their water chemistry can change over time. Testing your water on a regular basis will identify any changes that occur. This might allow you to adjust your water softener (if you have one), look for problems with scaling, or simply understand why your water tastes different.

There are many factors that can affect the hardness of your water, such as:

  • Changes in the source water
  • Treatment changes (like changing the type of salt you use in a softener)
  • Malfunctioning or misadjusted treatment equipment
  • Extra minerals dissolved in the water

I recommend testing your water once a month. Although water quality can change over time, things tend to move slowly in water treatment – on the scale of months, not days.

Monthly testing is good because it will allow you to notice any changes, but it isn’t so frequent that it becomes a pain.

What Do the Test Results Mean

Once you decide on how to test your water, it’s important for you to understand what the results mean. That way, you can decide whether or not to install a water softener or determine if you need to make adjustments to your water softener.

Different levels of hardness

One way to evaluate the meaning of your data is to compare your results with the general consensus of hardness.

Water hardness is classified into four categories:

  • Soft water: 0-60 mg/L (0-3.5 GPG)
  • Moderately hard water: 61-120 mg/L (3.5-7 GPG)
  • Hard water: 121 to 180 mg/L (7-10.5 GPG)
  • Very hard water: greater than 180 mg/L (>10.5 GPG)

For most of us, it’s good enough to know that our water is considered to be “Hard”. Whether it’s 7 GPG or 10.5 GPG doesn’t really matter because we’re going to need a water softener to prevent any problems.

Compare your results to others

Even if your test results fall into the “normal” range for hardness, it’s still important to understand how soft or hard your neighbors’ water is.

This is especially important if you live in an area with hard water. Water hardness can vary significantly from one location to another – even within the same town or city.

If your neighbors have hard water and you don’t, that might be a sign that there’s something wrong with your water treatment system. It may also be a sign that something is going on with your well.

Other Testing Methods for Hardness

In addition to the home test kits for hardness discussed above, there are other methods you can use.

Laboratory analysis

You can always send a sample of your water to a laboratory for analysis. This is the most accurate way to test your water, but it’s also the most expensive.

If you’re considering this option, I recommend using a certified lab. Certification is conducted by state oversight agencies and third-party organizations such as the National Environmental Laboratory Accreditation Conference (NELAC).

If you are concerned about the quality of your drinking water, you can contact a state-certified laboratory to have them test your water. The US EPA maintains a database of state agencies.

Local water department

If your drinking water comes from the local water department, they are required to test the water on a regular basis and make the results available to the public. Hardness is one of many tests they routinely perform.

In most cases, you can simply call the water department and ask for a copy of their water quality report. These reports will include information on hardness as well as other important parameters such as pH, alkalinity, and contaminants.

Tap Score

Tap Score provides laboratory water testing for hundreds of contaminants. They are a little different than other laboratories because they tailer their services to homeowners rather than consultants and industry. You can find a variety of water quality tests to meet your needs, including hardness.

  1. Step 1 – Collect Sample: Tap Score ships you everything you need to test your drinking water, including a guide on how to collect the sample.
  2. Step 2 – Ship to Lab: Ship the sample to Tap Score. The kit includes a shipping label to send it back.
  3. Step 3 – Get Report: After Tap Score analyzes your sample, they give you a report on what contaminants are in your water and how to address them.
Hardness Water Test
Tap Score has a simple to use test kit to measure hardness in your drinking water.

Tap score has a simple to use hardness test that will tell you how much calcium and magnesium are in your drinking water. They have a simple process that allows you to have access to accurate and reliable testing data.

Try Tap Score’s hardness test now

Does It Matter Where My Water Comes From

Drinking water generally comes from two sources – a public water supply or a private well.

Water that comes from a public utility is treated to meet specific quality standards. It is also tested routinely to ensure it meets those standards. The utility typically samples the water for important parameters such as pH, alkalinity, and contaminants.

Private wells are not subject to the same regulations as public utilities. This means you’re essentially on your own.

Test kits for well water

There are water test kits designed specifically for residential drinking water wells. These kits test for more parameters than hardness such as iron, fecal coliform bacteria, and other contaminants.

If you have a private well, I recommend testing your water at least once a year for all the important parameters – not just hardness.

Test kits for tap (public) water

If you get your water from a public utility, you can find test kits that are tailored to tap water. Since public water supplies are treated and routinely tested, you probably won’t need to work about bacteria and other contaminants.

However, tap water is disinfected with chlorine or chloramine, which requires specific testing requirements. There are tests that include chlorine, disinfectant byproducts, and other parameters that are unique to public water.


Can I test my own water hardness?

Yes, you can test your water for hardness yourself. There are water test kits available for hardness – you can find them online, your local hardware store, and home improvement stores.

Do water hardness test strips work?

Water hardness test strips are a quick and easy way to test your water hardness. They allow you to test your water hardness by dipping a test strip into your water. The results are available right away. These test kits don’t require skill or specific knowledge to use.

How do I tell my water hardness?

You can tell if your water is hard by looking for signs such as soap that doesn’t lather well, spots on dishes and glasses, or mineral buildup on fixtures. You can also test your water hardness with a water hardness test kit.

What is a good water hardness level?

A good water hardness level is anything below 3.5 grains per gallon. This is the highest hardness that is considered to be soft water. Read my article on what hardness setting to use for your water softener.

Do Brita filters remove hardness from water?

Brita filters do not remove hardness from water. These filters use particle filters and activated carbon to purify water, but these methods do not remove hardness.


Choosing the right water test kit for hardness is important. You can choose from a variety of tests, including strips, discs, titration kits, or digital meters. You can even use the old-fashioned soap test method.

Make sure to select a kit that is tailored to your specific water situation – whether you get your water from a public utility or private well. I hope this article was helpful in choosing the right water test kit for hardness.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children. You can also follow him on LinkedIn, Twitter and Facebook.

Recent Posts