Water Hardness by City

How hard is the water in your city? The table above collects the official hardness figure for 35 of the 40 largest U.S. cities, taken directly from each city’s own water utility: annual water quality reports (Consumer Confidence Reports) and the utilities’ hardness pages. Each row links to its source, so you can check the number and look for a newer report.

Sort any column by clicking its heading, or type a city or state to filter. The converter page explains the units if you need ppm, mg/L and grains per gallon.

What the numbers show

Hardness is mostly dissolved calcium and magnesium. Utilities usually report it as mg/L (the same as ppm) “as calcium carbonate”; dividing by 17.1 gives grains per gallon, the unit most softener makers use. This site uses the five-band scale from Nebraska and Penn State Extension: soft (under 17 mg/L, under 1 grain per gallon), slightly hard (17-60 mg/L, 1 to 3.5 grains), moderately hard (60-120 mg/L, 3.5 to 7 grains), hard (120-180 mg/L, 7 to 10.5 grains) and very hard (over 180 mg/L, over 10.5 grains).

Across the 35 cities with figures:

Band	Cities	Examples
Soft (under 17 mg/L)	2	Portland, Boston
Slightly hard (17-60)	5	Seattle, New York, Charlotte, Memphis, Sacramento
Moderately hard (60-120)	10	San Francisco, Austin, Detroit, Denver
Hard (120-180)	11	Houston, Chicago, Philadelphia, Washington DC, Los Angeles
Very hard (over 180)	7	Phoenix, San Diego, Las Vegas, San Antonio, Indianapolis

Hardness depends mostly on where a city gets its water. Water that soaks through mineral-rich rock picks up calcium and magnesium, so cities on groundwater or long rivers are often harder than cities fed by protected reservoirs. That is why neighbors can differ so much: Seattle and Portland are among the softest here, while Phoenix and Las Vegas are among the hardest.

Read your city’s number carefully

A single figure can hide a lot of variation, so check the notes column:

• Varies by area. About 15 cities draw on several supplies. In San Jose, groundwater averages around 288 mg/L while Valley Water’s treated supply is about 99. Los Angeles source averages run from 103 to 236. Your neighborhood can sit well above or below the typical value.
• Average of the reported range. Where a utility gave a range but no average, the typical value is the midpoint of that range or the average of its sources. The utility’s own range is shown next to it.
• Older data. Chicago (2014) and Dallas (2002) no longer publish hardness in their annual reports, so the most recent official figure is old. Chicago draws all its water from Lake Michigan, so its figure applies citywide. For either city, call your utility for a current number.
• Calcium hardness. Seattle’s figure and Nashville’s report row measure calcium hardness, which reads a little lower than total hardness.

Five large cities (Oklahoma City, El Paso, Tucson, Atlanta and Colorado Springs) don’t publish a readable hardness number, so they are left out rather than guessed. El Paso and Tucson describe their water only in words (“moderately hard to hard”, “hard”).

What to do with your number

1. Under about 60 mg/L (soft or slightly hard): a softener is rarely worth it for hardness alone. If you have spotting or taste issues, look at what else is in your water first.
2. About 60-120 mg/L (moderately hard): many households live with it; some add a softener for appliances or skin and hair comfort. Read hard water treatment options before buying.
3. Over about 120 mg/L (hard and very hard): scale on fixtures, water heaters and glassware becomes common. This is where a salt-based softener earns its keep. Enter your number in the softener size calculator to find the capacity you need, then compare models in the best water softener guide, which starts with a 48,000-grain Fleck at $1,995 for 2-4 person homes.

Salt-free conditioners change how minerals behave but leave the hardness in the water; the softener vs conditioner comparison covers the trade-offs.

How this table was compiled

Every value comes from the city’s own water utility, read in October 2026: the latest annual water quality report where it lists hardness, otherwise the utility’s hardness or water-quality FAQ page. Aggregator websites and equipment sellers were not used. Where a utility reported grains per gallon, the figure was converted at 17.1 mg/L per grain. The report year is shown with each source; pages without a date are marked as undated.

Utilities update their reports every year, and supplies change. If your utility has published newer numbers, trust those over this table. If your city is not listed, look for the hardness row in your utility’s Consumer Confidence Report, and if you are on a private well none of these figures apply to you: get a lab test.