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Best and Worst US States With the Hardest Water

Scott Winfield
Written by Scott Winfield
Last Updated on

Hard water is a common problem in the United States with over 85% of US water sources providing hard water to homes across the country. However, some states are more prone to this problem than others.

In this article we’ll discuss:

  • 5 US states with the least hard water
  • 5 US state with the hardest water
  • How water hardness levels are measured
  • What to do if you have hard water

How Water Hardness is Measured

There are many different ways to determine the hardness of water. Some measure it purely scientifically, while others attribute water hardness to the physical condition of their skin, hair or home appliances after using water.

Testing water

Scientifically, water hardness is measured by the concentration of calcium and magnesium ions in your water. It is expressed as calcium carbonate (CaCO3) and is taken from a sample of evaporated water.

Calcium carbonate is measured as mg/L or grains per gallon (GPG). To measure hard water, a sample of water is taken and heated to 61°C/141°F. When heated to this temperature, the bicarbonate in the water converts into carbonate.

The carbonate precipitates out with calcium to form calcium carbonate, which is then compressed and measured in mg/L. Grains per gallon represent one grain of calcium carbonate dissolved in one gallon of water.

Another unit traditionally used to measure water hardness is PPM. Parts per million describe the amount in fractions. It translates to one part of calcium carbonate in 58,000 parts of water or 17.1 parts per million. PPM and mg/L can be used interchangeably.

Soft water falls in the range of 0- 60 mg/L (0-3gpm), moderately hard water ranges from 61-120 mg/L (3-7gpm), hard water ranges from 121- 180 mg/L (7-15 GPM), and extremely hard water is anything over 180 mg/L (15+ GPM).

5 US States With the Least Hard Water

Here are the states who score best for soft water:

1. New York

New York is the first state on our list of places in the United States with the least hard water. The average hardness level for water in New York city is about 1.8 GPG.

About 9.5 million residents get their water from one of three watersheds. These are the Delaware, Croton, and Catskill systems.

90% of the water provided to New York City residents is from the Delaware and Catskill systems. Proper funding/ allocation of resources can be thanked for the refined water present in New York, as the state (specifically New York City) takes several precautions to ensure good water quality. This includes a state-of-the-art disinfection treatment and incentives for water purificators.

2. North Carolina

Another state that is known for having soft water is North Carolina. This state has a reported water hardness of 46 PPM, which falls comfortably in the category of soft water.

Charlotte, North Carolina – the most populous city in the state – has an average water hardness level of just 28 PPM.

Most cities in North Carolina range from 28-52, but there are exceptions, including New Bern, Jacksonville, Hickory, and Greenville (having scores of 100 PPM, 111PPM, 215 PPM, and 85 PPM, respectively). These scores make up less than half of the cities in the state and seem to be outliers. The difference in numbers is likely due to the geological location of those cities.

3. New Hampshire

According to the United States Geological Survey, New Hampshire has an average water hardness level of around 39 PPM. Most of the cities in New Hampshire fall into the range of 14PPM to 29 PPM, with Somersworth having the lowest PPM.

The city of Portsmouth, however, has a reported water hardness level of 101PPM – the only city with a PPM over 29. The water from Portsmouth is sourced from the chalk (carbonate rock formed underwater) of the South Downs. The moderately-hard water found in residents’ homes results from this carbonate remaining in the water as it travels.

4. Oregon

Next on the list is the state of Oregon, known for its diverse geological landscapes and plenty of water. Several major rivers run through Oregon, including the Willamette, Snake, and Columbia rivers. The state has an average water hardness of 29 PPM.

Portland, Oregon’s most populous city, has a water hardness of 12 PPM, classified as very soft. The Bull Run watershed is one of the two main water suppliers to Portland, and the Columbia South Shore well field draws water from the aquifers it is located above.

The capital of the state, Salem, has a water hardness level of 18 PPM, making it another city where its residents enjoy very soft water.

5. Hawaii

Hawaii is a gorgeous vacation destination to outsiders, but for its residents, the state is their home, and they take care of their water supply quite well, scoring an average water hardness of 34 PPM (according to the USGS). Groundwater is the primary provider of Hawaii’s water as it contributes to 99% of the state’s domestic water and around 50% of the state’s freshwater.

The soft water cities in Hawaii include Kaanapali and Hilo, both of which have a reported water hardness of 17PPM. Maui is the only city with a water hardness above 34PPM with a hardness of 110 PPM.

Hawaii has some of the best drinking water in the country because the lava rocks naturally filter the aquifers, and each of the 8 islands has individual departments that provide their consumers with high-quality water.

You might also be interested in: Best & Worst Tap Water in the US: State-by-State Analysis

5 States With the Most Hard Water in the US

Now that we’ve taken a look at our winners for soft water, let’s examine the top contenders for the hardest water in the US.

1. Indiana

Indiana has one of the highest concentrations of calcium carbonate in the country. The levels typically range from 200- 350 mg/L in its most populous city, Indiana, according to the 2020 Water Quality Report for Carmel.

This is well above the norm. The natural levels of calcium and magnesium found in the region are directly responsible for the high levels of hardness in Indianapolis.

Though Indianapolis has very hard water, it is not the highest in the region or even the state. The cities of Somerset and Lafayette have the hardest in the state, with recorded hardness at 400 mg/L and 382 mg/L, respectively. Residents of Indiana have to rely on in-home water softener systems to combat the effects of hard water.

2. Nevada

Another state with the highest levels of hard water in the United States is Nevada. Las Vegas is a city most known for its nightlife. Casinos, resorts, and many different kinds of entertainment can be found here for residents and people passing through, but homeowners in the state also have real concerns about hard water.

With an average of 16 GPG, Las Vegas residents deal with hard water on a daily basis, making the situation unappealing to live with at best and a danger to their plumbing at worst.

The source of the hard water in Las Vegas specifically can be traced to Lake Mead, the source of about 90% of its water. Lake Mead’s water comes from the Colorado River and picks up calcium and magnesium as it flows. To make matters worse, local water filtration does not sufficiently remove these minerals.

3. Minnesota

Minnesota’s hard water is an issue that residents of the state deal with on a daily basis. There is a larger range in this state than the others listed so far. The lowest reported hardness level was 85 mg/L, while the highest average was reported at 547 mg/L.

The main reason for the high levels of calcium carbonate is due to water being sourced from the Mississippi River, though it starts as soft water, flows over rocks, and absorbs the limestone bedrock. Limestone is rich in calcium and magnesium, which results in a high grain per gallon ratio.

The twin cities – Minneapolis and the St. Paul metropolitan area – are most known for having high mineral concentration levels.

4. Texas

Texas has the misfortune of being located on top of the water heavily saturated with limestone. The levels of hardness range from 15-20 GPG on average.

The most commonly reported effects of hard water in Texas include stains on glassware, soap scum, and itchy/ irritated skin after washing.

San Antonio and Austin, Texas are the highest in the region as they lie directly over the Central Texas water containing high levels of calcium and magnesium. Though water softeners are not as common in Texas as in other regions of the country, they serve to make the negative effects of hard water much less prominent.

5. California

Hard tap water is a big problem in California. Much like Texas, the large surface area of the state means that water from groundwater sources and local rivers has to travel long distances to get to residential faucets. This means the likelihood of having hard water in this state is much higher than in most states in the north/ northeast United States.

Californians, especially in Los Angeles, experience hard water from their municipal water sources because of the lack of filtration, leaving plenty of calcium and magnesium behind.

What To Do if You Have Hard Water

While hard water does not pose a threat to your health or the health of your loved ones, the day-to-day hassle and the danger it poses to plumbing and appliances is reason enough to be cautious.

Hard Water

Signs of Hard Water and How To Test for It

Common signs that you have hard water (other than where your home is located) include:

  • Noticing film on your hands when you are finished washing them with soap and water
  • Spots appearing on glass and silverware when unloading your dishwasher
  • Low water pressure in your home
  • Residue on your faucets
  • Dull laundry
  • Itchy/ dry skin after washing.

Issues in wash-quality when it comes to dishes, clothes, and your hands/ body are due to the calcium in the hard water reacting with the soap to form soap scum (calcium carbonate deposits). Mineral deposits can also be carried to and left in your pipes, causing a building that stops water from flowing out of your faucets properly.

There are also DIY tutorials and water testing kits you can order online or in- stores.

How To Fix Hard Water

As mentioned above, there are no adverse health effects when it comes to using and drinking filtered hard water. However, there are solutions for those who live in areas with hard water and want to leave the hassle behind.

The most popular method for softening water is installing a water softener. This is done by adding a clip-on/ twist on the shower and faucet head that filters out the water right before dispensing.

Another method is hiring a company to install a water purifying system on your home’s main water tank. There are several alternatives that you can use to soften your water naturally. These include:

  • Boiling your water before you consume it
  • Using baking soda in the water you intend to cook with
  • Adding washing soda to your clothes when washing them

These methods, while generally helpful, may lead to varying degrees of success depending on the overall hardness of the water you’re dealing with.

Even though 80% of the United States does not currently have soft water, only 30% of residents use water softeners. This may be due in part to some of the down sides of using these softening methods.

Cons of Water-Softening Solutions

Some cons of softening your water to keep in mind are that the process is only recommended to eliminate calcium and magnesium from water. Water softener does not remove chlorine, lead or any other minerals or chemicals that may be displeasing to have in your water.

The consensus, however, is that water softening is a relatively painless and inexpensive procedure that can quickly and efficiently improve the quality of your water.


What water hardness boils down to is the mineral content. High concentrations of calcium carbonate in your water can lead to the buildup in your pipes and unsavory film/ soap residue on your dishes, clothes, and body.

Certain cities across the United States are more prone to hard water than others, particularly those in the Midwest and West coast.

Protecting your home starts with being educated on the water hardness of your city and knowing how to soften your water if needed. Water testing kits and water filter/ softener systems are available online and in stores. Home remedies are also available for anyone who prefers natural methods of softening their water.

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Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
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