What is the Water Hardness Scale and What’s a Good Score?

What is the Water Hardness Scale and What’s a Good Score?
One of the most common water issues homeowners deal with is hard water - 85% of U.S. homes have hard water.

Water classified as “hard” contains dissolved hardness minerals such as calcium and magnesium. These minerals are the source of scale buildup on faucets and appliances, and the poor performance of soap and detergent in showers and laundry.

While it’s more likely than not your water has some degree of hardness, assessing the level of hardness is key to understanding the risks of its effects on your home, and for choosing the most effective treatment solution.

How to test your water for hardness

If your water source is a municipal water treatment facility, you can check out your local Consumer Confidence Report, (CCR) an annual drinking water quality report from your water supplier, which should include a measure of your water’s hardness.

If you have a private well, you can purchase a water test kit.

While there are do-it-yourself water tests available that test hardness alone, if you’re serious about evaluating your water quality, we recommend purchasing a more complete water test.

You should test your water not only to determine the level of hardness, but also to see if there are other contaminants that need to be treated. The exact makeup of your water issues will guide you in the selection of the appropriate water treatment system for your home.

Purchase a water test kit

What level of hardness needs treatment?

The test results for the hardness of your water will be reported in grains per gallon (gpg), parts per million (ppm) or milligrams per liter (mg/l). One grain of hardness equals 17.1 ppm or 17.1 mg/l of hardness.

This measure is the number of units of calcium carbonate (a concentration of dissolved calcium and magnesium) dissolved in water. For example, 1 ppm would equal one unit of calcium carbonate dissolved in one million units of water.

Water hardness is classified as:
  • Soft: < 1 gpg (0-17.1 ppm)
    • This level of hardness does not require softening.
  • Slightly hard: 1-3.5 gpg (17.1-60 ppm)
    • This level of hardness likely does not require softening.
  • Moderately hard: 3.5 - 7.0 gpg (61-120 ppm)
    • At this level, you may see signs of hardness such as spotted dishware
  • Hard: 7.0 - 10.5 gpg (121-180 ppm)
    • This level of hardness will cause scaling on appliances
  • Very Hard: > 10.5 gpg (over 180 ppm)
    • This level of hardness will show all symptoms of hardness

Some water hardness scales also include “Extremely Hard” - >15 gpg (over 257 ppm)

Water that is classified as “Moderately Hard” (3.5 gpg or 61 ppm) or above would benefit from treatment by a water softener or water conditioner.

The harder your water, the more likely and serious the adverse effects in your home, such as chalky buildup on your fixtures, shortened lifespan of appliances, and even clogged pipes and reduced water flow.

Read more about testing your water

Read more about home water filtration systems

While hard water itself may not pose a risk to your health, other contaminants that often accompany it - such as iron and manganese - may have adverse effects.

Read more about well water safety

Read more about hard water

How to treat hard water

Successful treatment of your water issues will depend on both the level of hardness, and if there are other contaminants present in the water such as iron.

Read more about whole house water filtration systems

Hard water treatment will usually include either a water softener or a salt-free water conditioner.

Water softeners

A salt-based water softener system uses a mineral tank and a brine tank, typically installed at the point that water enters a home so that all of the water in your home benefits.

Softeners use a process called ‘ion exchange’ to trade the hard water minerals for sodium.

The hardness minerals are trapped, while softened water flows through to the home. During the softener’s regeneration cycle, the hardness minerals are washed away down the drain.

Salt-free water conditioners

Salt-free, or water conditioning, systems don’t trap the hardness minerals, but help prevent the scale buildup caused by hard water.

Because these systems don’t technically remove the hardness minerals, this process is known as “conditioning” the water, not softening it.

Water Conditioners work by converting hardness minerals to a crystalline form which can’t bind to the insides of your pipes or appliances. This reduces the formation of scalr, and can even reduce existing scale.

These systems don’t need to regenerate or have access to a drain because salt-free systems don’t collect any materials.

However, for very hard water, a salt-free conditioner will not be as effective as a traditional water softener and is not recommended.

You will also need a pre-treatment filtration system if your water has iron, manganese or copper.

Read more about water softeners


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If you want to upgrade or treat more complex issues, you can review the full line of treatment systems, or call or contact a Tier1® customer service expert to discuss your options.

Call for personal recommendations from Tier1® customer service at 1-855-378-9116.

Hard water is simple to identify and treat

While hard water is one of the most common issues homeowners face, it’s also fairly easy to identify and treat.

When you test your water to identify all your water issues, and choose an appropriate filtration solution, both your home and your health will benefit.