Water Hardness by City, From Each Utility's Own Report

The utility publishes two different numbers on its own website

The Las Vegas Valley Water District's facts page, under the heading "How hard is our water?", says the hardness is 291 parts per million or 17 grains per gallon. Further down that same page, under home treatment systems, it says 280 parts per million or 16 grains per gallon. The 280 figure is the one that matches their current annual report, where it appears as a tip for setting a water softener rather than as a tested result in the contaminant table.

Both are published by the utility. Neither is wrong. If you are sizing equipment off one of them, it is worth knowing the other exists. And note that North Las Vegas and Henderson are separate water systems with different water, so neither figure applies to them.

Two datasets that disagree, four years apart

LADWP publishes current hardness by source: the Los Angeles Aqueduct Filtration Plant at 103 mg/L, the well fields at 115 and 116, and the three Metropolitan Water District plants between 140 and 236, all 2025.

It separately publishes hardness by named area of the city, which is the only version a homeowner can actually use and the only one given in grains per gallon: San Fernando Valley and Western LA at 8.6 gpg, Silver Lake through South LA at 9.8, Eastern LA and the Harbor at 16.3. LADWP labels that table "from 2022" itself, and the gap matters: the Northern Combined Wells averaged 230 mg/L in 2022 and 115 mg/L in 2025.

So the usable version is four years old and the current version cannot be mapped to a neighbourhood without doing the translation yourself. LADWP says so plainly: hardness varies greatly across the city, and most areas can receive any of the supplies during repairs or unusual events.

Forty-one values, one per ZIP code

JEA does not publish a citywide figure. It publishes a table of forty-one ZIP codes with hardness in both parts per million and grains per gallon, plus a hardness classification for each. The spread runs from 120 ppm, 7 grains, in 32234 up to 372 ppm, 22 grains, in 32081. In between: 32202 at 239 ppm, 32210 at 194, 32216 at 341.

JEA explains why, and the explanation is the useful part: each value is the average of the wells serving that plant, and hardness is highest around St Johns Forest and lowest around Cecil Commerce. It is the most honest treatment of hardness on this list, and JEA never states which year the sampling comes from.

The utility declines, and explains why

Truckee Meadows Water Authority publishes no hardness figure in its annual report. Its FAQ says, verbatim: "TMWA typically does not test individual homes for hardness concentrations. Your water's hardness varies considerably depending upon whether or not you live near a production well and what time of year it is. In the summer you could be getting a blend of surface and well water. In the fall and winter you're receiving mostly treated surface water which would have a typical hardness between 3 to 4 grains."

There is no published summer figure. That is not an oversight. It is a utility refusing to give a single number for something that genuinely is not a single number, which is more useful than a tidy average would have been.