How to Measure Water Hardness

Hard water is a common issue that many people have to deal with, and it has its pros, often the cons far outweigh the benefits. If you’re not sure whether the water coming out of your faucets is hard or soft, we’ve got you covered.

In this article, we outline how hard water is measured and how to test your water to receive your hard water number to determine just how hard your water is.

What is Hard Water?

Signs of hard water

Signs of hard water

Hard water refers to water that contains dissolved hardness minerals, typically calcium and magnesium. If you have hard water coming out of your fixtures, you’ll be able to see the signs around your household. Here are some things to look out for:

  • White water stains on glassware
  • Scale and deposits on tiles, faucets, toilets and showers
  • Dry, stretched skin
  • Dull, lifeless hair
  • White residue on the bottom of kettles, carafes and humidifiers
  • Soap, shampoos and detergents won’t lather
  • Faded, worn out looking laundry
  • Mineral deposits in steam irons

These are just some of the signs of hard water, but it goes to show the extent of impact hard water can have on your home. This is why many people buy a water softening system to treat hard water. But to buy such a system, you need to know how hard your water is. Because hardness comes in different levels, knowing the hardness level will help you to purchase the right capacity water softening system.

How is Hard Water Measured?

Hard water is measured in parts per million (PPM) or in milligrams per liter (ml/L) but when we talk about hardness, we tend to speak in grains per gallon (GPG). It’s easier to understand and visualize. The good news is that PPM and ml/L can be converted to GPG, and vice versa.

PPM is exactly what it sounds like. It measures the number of hard water minerals in a million units of water. ml/L measures the amount of hard water minerals in a liter of water.

GPG comes from an ancient Egyptian system of measurement, where a grain refers to the weight of a dry grain of wheat.

To convert between these units, simply divide the PPM or ml/L by 17.1 to get the amount in GPG. 

According to the Water Quality Association (WQA), the soft to hard levels of water can be categorized as follows:

Soft0 – 17.10-1
Slightly Hard17.1 – 601 – 3.5
Moderately Hard60 – 1203.5 – 70
Hard120 – 1807.0 – 10.5
Very Hard180 +10.5 +

Once you have the GPG level of your water supply, you’ll then know how hard your water is and what to do about it. To find out your GPG level, you’ll need to test your water.

How to Test for Hard Water

Man measuring water hardness

There are a few ways to find out the hardness level of your water. Some of these methods can be done right at home.

Water Quality Report

Before you take testing into your own hands, it’s worth checking if your water supplier provides a periodic water quality report. Most public water supplies will give their customers an annual report detailing the quality of the water and what contaminants are in it. You can either request this or check online for it.

Home Test Meter

This is probably the easiest way to do this right at home. Simply purchase a test meter that measures the Total Dissolved Solids (TDS) in your home, like this one. It’ll show you the number of contaminants and minerals in your water.

However, while the meter will give you a number of the PPM in your water, it won’t specify what these contaminants are. You won’t know for sure whether the reading is due to hardness minerals or a range of other contaminants. On the bright side, you’ll get an indication of your water quality and can test further if the meter shows a high contaminant level.

Home Test Kit

Another way to test for water hardness at home, try a home test kit like this one which works with more specificity. This type of test kit measures the total hardness in grains. Just make sure you follow the instructions to a T to ensure the results you receive is accurate.

Professional Laboratory

If you want a professional to handle testing your water, you can have a water testing laboratory do the job for you. Once they receive a sample of your water, they’ll be able to test it and let you know what’s in it.

What’s Next?

If you’ve tested your water and you find out your water is hard, don’t panic. Over 85% of homes in the US have hard water, with 13 GPG being the average. This equals to a Very Hard water level, which can be damaging on your home. You’ll start noticing the impact of hard water on your home from around the 7 GPG mark. No wonder over 30% treat hard water with water softening systems.

Hard water isn’t known to be detrimental to health and is considered safe for drinking. In fact, many people love the taste of hard water compared to soft water. However, hard water is frustrating and has many negative effects on your household.

If the option is available to you, we recommend installing a water softening system for your entire home. If you only want softened water in your shower, consider a shower water filter for hard water.

From the different water softening systems available, salt-based systems are proven to be more effective and comprehensive at treating hard water. However, salt-free systems are easier to maintain and alleviate one of the most damaging aspects of hard water – mineral buildup.

To learn how to choose a water softening system, check our step by step guide here.

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