If you are a homeowner in the United States, there is a good chance that your city has hard water. In fact, according to the American Water Works Association, approximately 85% of Americans receive their drinking water from systems with hard water. So, what exactly is hard water? And which cities have hard water?
The six US cities with the hardest water are Indianapolis, Las Vegas, Minneapolis, Phoenix, San Antonio, and Tampa. The average hardness for these cities is 18 grains per gallon or 309 parts per million. For perspective, this is almost 5 times as much hardness ions as soft water has.
In this article we explore which cities in the US have hard water. We also cover hard and soft water in the various states and what you can do to address hard water in your drinking water.
Read my comprehensive article about water softener salt.
Table of Contents
What Is Hard Water
Hard water is water with high concentrations of calcium and magnesium. These two minerals are known as hardness. Hard water is most commonly found in regions with limestone or chalk deposits.
Hardness concentrations are usually presented in units of milligrams per liter (mg/L) of calcium carbonate. These units are the same as parts per million (ppm).
Hardness is also reported in grains of hardness per gallon of water – grains per gallon (gpg).
The following table presents the classifications of water hardness as both mg/L of calcium carbonate and grains per gallon.
| Water Hardness Classification | ||
| Water Hardness | grains per gallon (gpg) | milligrams per liter (mg/L) |
| Soft | < 1.0 | < 17.1 |
| Slightly Hard | 1 to 3.5 | 17.1 to 60 |
| Moderately Hard | 3.5 to 7.0 | 60 – 120 |
| Hard | 7.0 to 10.5 | 120 – 180 |
| Very Hard | 10.5 + | 180 and over |
Problems caused by hard water
Hard water can cause several issues in your home. It can reduce the efficiency of your water-using appliances by leaving deposits on pipes and fixtures, causing them to clog or become corroded. Additionally, it can make cleaning difficult, as soap doesn’t lather properly with hard water.
As a result, you may find yourself using more detergent and cleaners to get the same level of cleanliness. Lastly, hard water can also leave behind mineral deposits, known as scale, on your dishes and other items.
Hard water can reduce the quality of your water if left unchecked.
Where does hardness come from?
There are two types of minerals that serve to make your drinking supply “harder.” These substances, calcium and magnesium, can be found in the soil and bedrock that groundwater flows through. The longer water sits in contact with these minerals, the more it dissolves them.
Areas where drinking water comes from underground aquifers tend to have higher levels of hardness than those that get their water from rivers and lakes. This isn’t always the case, but it is true for most cities.
Testing for Hard Water
Testing your home’s water supply for hardness is necessary to determine what safety and quality concerns you may have. You can easily test your own water at home with a DIY test kit. Or, if you’d rather leave it to the professionals, you can contact your local water supplier and ask them to test the hardness of your water.
If you get your water from a public water supply, the utility conducts routine testing. You can call them and ask for a copy of the most recent water quality report. This report should tell you whether your water is hard or not.
Read my article about testing for hardness.
Hard Water in the US
A large part of the United States has hard water. The US Geologic Survey reports that 85% of Americans drink hard water.
US water hardness map
The majority of the USA has hard water, so it’s likely that you live in an area with hard water. The map below depicts the different levels of water hardness across America.
There are many factors that determine the hardness of your drinking water. One important factor is where you live. In general, states can be divided into four groups that describe their water quality:
- very soft water
- soft water
- hard water
- very hard water
The following table summarizes the relative hardness of drinking water by state.
| Water Hardness by State | |
| State | Water Hardness Rating |
| Washington | Very Soft Water |
| Oregon | Very Soft Water |
| Arkansas | Very Soft Water |
| Mississippi | Very Soft Water |
| Louisiana | Very Soft Water |
| Alabama | Very Soft Water |
| Georgia | Very Soft Water |
| North Carolina | Very Soft Water |
| South Carolina | Very Soft Water |
| Delaware | Very Soft Water |
| Connecticut | Very Soft Water |
| Vermont | Very Soft Water |
| New Hampshire | Very Soft Water |
| Massachusetts | Very Soft Water |
| New York | Very Soft Water |
| Hawaii | Soft Water |
| Alaska | Soft Water |
| North Dakota | Soft Water |
| Minnesota | Soft Water |
| Missouri | Soft Water |
| Tennessee | Soft Water |
| West Virginia | Soft Water |
| Pennsylvania | Soft Water |
| Nevada | Hard Water |
| Idaho | Hard Water |
| Montana | Hard Water |
| Kansas | Hard Water |
| Oklahoma | Hard Water |
| Texas | Hard Water |
| Michigan | Hard Water |
| Kentucky | Hard Water |
| Ohio | Hard Water |
| New Mexico | Very Hard Water |
| Utah | Very Hard Water |
| Western Texas | Very Hard Water |
| Wisconsin | Very Hard Water |
| Indiana | Very Hard Water |
| Florida | Very Hard Water |
Which states have hard water?
States with high levels of calcium and magnesium in their water sources, have hard water. Surprisingly, the states with hard water aren’t clustered together.
There are several reasons why a particular state has hard or very hard water. These include:
- soils that have high levels of calcium and magnesium
- areas with limestone
- rivers that flow through regions with high mineral content
The 5 states with the hardest water are:
| States with the Hardest Water | |
| State | Average Hardness |
| Indiana | 20.4 gpg |
| Nevada | 16 gpg |
| Minnesota | 32 gpg |
| Texas | 20 gpg |
| California | 17.5 gpg |
Which states have soft water?
About 15% of the US has soft or very soft water. These areas are fortunate enough to have soft water, which is ideal for drinking, cooking, and other domestic uses.
The 5 states with the softest water are:
| States with the Softest Water | |
| State | Average Hardness |
| New York | 1.8 gpg |
| North Carolina | 2.7 gpg |
| New Hampshire | 2.3 gpg |
| Oregon | 1.7 gpg |
| Hawaii | 2.0 gpg |
Cities with hard water
Some regions of the United States experience problems with hard tap water, but some cities are more prone to this issue than others. If you live in one these areas, it is important that your home has a water softener.
These six cities have especially hard water:
- Indianapolis, IN: It’s no secret that the water in Indiana is hard. The average level of dissolved minerals stands at 12-20 grains per gallon, which makes it much higher than most other parts on America. Challenges with water hardness are common in Indiana because a majority of the state sits on limestone bedrock.
- Las Vegas, NV: 90% of Las Vegas’ water comes from Lake Mead. The lake is fed from the Colorado Rier, which picks up calcium and magnesium along its journey. Due to this, the water’s hardness averages 16 grains per gallon.
- Minneapolis, MN: Half of Minnesota residents get their water from groundwater, and they have very hard water. The rest of the state gets its water from the Mississippi river, which is relatively soft.
- Phoenix, AZ: The drinking water in Phoenix has an average water hardness of 12–17 grains per gallon. The water is hard because it comes from the Colorado, Verde, and Salt Rivers which have very high levels of dissolved minerals.
- San Antonio, TX: San Antonio’s drinking water has very hard water – the average concentration is 15-20 grains per gallon. This is because much of central Texas has a lot of limestone which consists mostly of calcium and magnesium.
- Tampa, FL: Virtually all of Tampa’s drinking water comes from underground aquifers. The groundwater flows through mineral-rich soil that has high levels of calcium and magnesium.
Los Angeles
Los Angeles has hard water with a water hardness of around 127 mg/L. This is the same as 7.4 gpg. To learn more about water hardness in Los Angeles and how it can affect your daily life, check out our article on water hardness in Los Angeles.
Nashville
Nashville tap water has an average hardness of 79 mg/L or 5 grains per gallon, which is considered moderately hard. This means that the water in Nashville has a moderate amount of minerals that can potentially cause scaling in pipes and appliances. If you’re curious to learn more about the water hardness in Nashville, check out our article on Hard Water in Nashville.
Denver
Denver’s tap water is classified as moderately hard, with an average hardness of 97.5 mg/L or 5.8 grains per gallon. To learn more about how the hardness of Denver’s water can impact your daily life and how to address it, check out our article on Hard Water in Denver.
Houston
If you live in Houston, you may have noticed that your tap water is on the hard side. According to the Texas Commission on Environmental Quality, the average water hardness in Houston is 9.9 grains per gallon or 179 parts per million. To learn more about hard water in Houston and how to address it, be sure to check out our article on Hard Water in Houston.
Seattle
Seattle has relatively soft water, with an average water hardness of 1.4 grains per gallon or 21.5 milligrams per liter as calcium carbonate. This is much lower than the average water hardness in other cities in the US. If you want to learn more about the water hardness in Seattle, check out our article Hard Water in Seattle.
Norfolk
Norfolk has tap water that falls between soft and moderately hard. The water hardness in Norfolk varies between 29 and 56 parts per million, with an average of 41 ppm. While not considered hard, this level of hardness can still cause some scaling and mineral buildup in pipes and appliances over time. Check out our article on hard water in Norfolk to learn more about water hardness and how to address it.
New York
New York City’s tap water is considered to be moderately hard with an average hardness of 65 parts per million (ppm). The hardness of the water can range from 86 to 154 ppm. To learn more about the quality of New York City’s water, check out our article Hard Water in New York City.
Boston
Boston is known for having soft water. The water hardness in Boston is considered to be low, with an average range of 6 to 20 mg/L of calcium carbonate or 0.4 to 1.2 grains per gallon. If you’re interested in learning more about the water quality in Boston, check out our article on Hard Water in Boston.
Chicago
Chicago’s water is known for being hard. The city’s average water hardness ranges from 130 to 150 mg/L of calcium carbonate, which is equivalent to 7.6 to 8.8 grains per gallon. Hard water is common in many areas of the Midwest, and it can cause various issues with plumbing and appliances. If you’re curious about how to deal with hard water in Chicago, be sure to check out our article on Hard Water in Chicago for more information.
Memphis
If you live in Memphis, you’ll be pleased to know that the tap water is considered soft, despite being located in an area with high mineral deposits. The average water hardness in Memphis is only 55 parts per million (ppm) or 3 grains per gallon (gpg), which is below the 75 ppm threshold for soft water. So, check out Hard Water in Memphis to learn more.
Knoxville
Knoxville’s tap water is moderately hard, with an average hardness of 84 ppm or 4.9 grains per gallon. While this level of hardness is not extreme, it may still cause buildup in pipes and appliances over time. To learn more about the effects of hard water and how to deal with it in Knoxville, check out our article on hard water in Knoxville.
San Francisco
San Francisco has relatively soft water with an average hardness of around 47 ppm. If you’re interested in learning more about the quality of San Francisco’s water, check out our article on Hard Water in San Francisco.
Austin
Austin’s tap water has a moderate level of hardness with an average of 84.5 ppm. If you live in Austin and want to learn more about the effects of hard water on your home, check out our article on Hard Water in Auston, TX.
Dallas
Dallas water has an average hardness of 131 milligrams per liter (mg/L), making it hard according to the USGS classification. Check out our article on Hard Water in Dallas for a detailed discussion.
San Antonio
San Antonio’s tap water has a high level of hardness, with an average hardness of 357 ppm or 21 grains per gallon. This level of hardness is considered very hard and can lead to mineral buildup in pipes and appliances. If you’re a homeowner in San Antonio, it’s important to understand the effects of hard water and how to address them. Check out our article on hard water in San Antonio, Texas to learn more about this topic.
San Diego
San Diego’s water is known for being very hard, with an average hardness of 276 mg/L or 16 grains per gallon. This is considered very hard by USGS standards. Hard water can cause various issues with plumbing and appliances. If you’re curious about how to deal with hard water in San Diego, be sure to check out our article.
Sacramento
Sacramento’s water is known for having a hardness of 150 ppm or 9 gpg. This level of hardness can also cause issues with plumbing and appliances. If you’re living in Sacramento and struggling with hard water, be sure to check out our article on hard water in Sacramento.
Naples
Naples, did you know that your water has a hardness of 65 ppm or 3.8 gpg? While this level of hardness is considered moderately hard, it can still lead to mineral buildup in your plumbing and appliances. Check out our informative article on hard water in Naples.
Orlando
Orlando residents, did you know that your water has a hardness of 129 ppm or 8 gpg? This makes it classified as hard water which can lead to mineral buildup in your plumbing and appliances. If you’re concerned about the quality and safety of your drinking water, check out our informative article on hard water in Orlando.
Washington DC
Washington DC’s water is moderately hard with an average hardness level of around 122 mg/L or 7 grains per gallon. While it may not be as hard as San Diego’s water, it can still cause issues with plumbing and appliances. If you want to know more about hard water in Washington DC, make sure to read our article.
Portland
Portland’s water is considered soft with a hardness level of 12 ppm or 0.7 grains per gallon. Soft water is ideal for your plumbing and appliances. If you’re interested in learning more about hard water in Portland, be sure to read our article.
Boise
Boise, Idaho is known for its moderately hard water with an average hardness of 108 ppm or 6.3 gpg. If you’re a Boise resident struggling with hard water issues, you’ll want to check out our article on hard water in Boise.
What to Do About Hard Water
Hard water can be a nuisance and has been linked to decreased energy efficiency, damage to plumbing, and even health issues. If you live in one of the cities above or have hard water in your home, you’ll need to treat your water to reduce the hardness.
Methods to soften water (removing hardness)
The most effective way to soften your water (reduce the hardness) is to install a water softener. A water softener works by exchanging hard ions (calcium and magnesium) for soft ions (sodium). Water softeners also require maintenance, like regular regeneration of the resin bed.
Other methods to reduce water hardness are not as effective and may include reverse osmosis systems or chemical ion exchange.
How do water softeners work
Water softeners use a process known as ion exchange to remove hardness from the water. The process works by exchanging hard ions (calcium and magnesium) for soft ions (sodium).
The ion exchange resin is placed in a tank, and the hard water flows through the media. As the water contact the resin, the calcium and magnesium ions adsorb onto the surface of the media. The softened water is then sent to the rest of the house for drinking, bathing, and cooking.
Eventually, the IX resin becomes saturated with hardness ions. At this point, it is regenerated with salt brine to flush away the calcium and magnesium ions. These ions are exchanged for sodium ions in the brine solution.
Once the resin has been regenerated, it is flushed with clean water and then put back into service.
FAQs
Which areas have the hardest water?
The areas of the US with the hardest water include Indianapolis, Las Vegas, Minneapolis, Phoenix, San Antonio and Tampa.
What is the best method to soften water?
The most effective way to soften your water is by installing a water softener. This type of system removes hardness from the water using a process called ion exchange.
How common is hard water?
Hard water is very common. In the US, approximately 85% of homes have hard water. Of these residences, approximately 33% have a water softener to reduce the hardness.
Which countries have hard water?
Hard water is a problem for many people all over the world. Countries known for having hard water include the United Kingdon, the US, Canada, and Australia.
Final Take
Hard water is a fact of life for the vast majority of people in the US. If you live in cities with hard water, like Minneapolis, Phoenix, San Antonio, or Tampa, it’s important to treat your water to reduce the hardness. The best way to do this is by installing a water softener. This type of system removes hardness from the water using a process called ion exchange and requires regular maintenance. With the right treatment, you can ensure your drinking water is safe and of high quality.