How Hard Is Salt Lake City Water? Reading the City’s Own Numbers
How hard, in one line
Hard, nearly everywhere in the city, and harder from some sources than others. Salt Lake City Public Utilities publishes the figures in its annual water quality report, and the 2026 edition, covering 2025 data, lists total hardness for each source along with a calculated grains-per-gallon figure.
The numbers by source
Grains per gallon is the unit softener sellers and plumbers use; milligrams per litre is what labs report. One grain per gallon is about 17.1 milligrams per litre. The common classification calls water above about 7 grains hard and above about 10.5 very hard. The table further down this page lists every source in the report in both units.
Why your tap may change through the year
The city draws on mountain streams (City Creek, Parleys Creek, Big Cottonwood and Little Cottonwood), on deep wells and springs, and on treated water bought from the Metropolitan Water District of Salt Lake and Sandy and the Jordan Valley Water Conservancy District. Its report explains that in summer, when stream runoff falls, groundwater from wells is blended in to meet demand and keep pressure up.
The wells are where the high numbers are: 9.6 to 33.4 grains. So a house that gets mostly treated stream water in spring may see harder water in late summer. Spotting on glasses and shower doors that gets worse in August is the system working as designed.
What hardness does inside a house
- Scale in the bottom of tank water heaters, which makes them rumble and shortens their life
- Buried and burned-out lower elements in electric water heaters
- Error codes and lost flow in tankless heaters that are not descaled
- Clogged aerators and shower heads, and faucet cartridges that drip or stick
- White crust on fixtures and spots on glass, and more soap needed for the same lather
How to test your own water
Test strips from a hardware store give a reasonable reading in a minute. Test at the kitchen tap with cold water that has run for a short while. If you already have a softener, test before and after it to see whether it is working. Do it twice, in spring and late summer, and size anything you buy for the higher figure.
Is hard water unsafe?
No. Calcium and magnesium are not a health concern at these levels, and the city reports that it issued no drinking water violations in 2025. Hardness is a plumbing and cleaning problem, not a safety one. Softening adds a little sodium, which is why many households keep one unsoftened tap for drinking.
If you are not on Salt Lake City water
Millcreek and Holladay are partly on city water and partly on other systems, West Valley City is on the Granger-Hunter Improvement District, and other suburbs have their own suppliers. Each publishes its own annual report. Find the supplier name on your water bill and look up that report.
| Source | Total hardness (mg/L) | Grains per gallon |
|---|---|---|
| Big Cottonwood treatment plant | 136 | 8.0 |
| Parleys treatment plant | 175 | 10.2 |
| City Creek treatment plant | 212 | 12.4 |
| City wells and springs | 154 to 571 | 9.6 to 33.4 |
| Metropolitan Water District, Little Cottonwood plant | 152 | about 8.9 |
| Metropolitan Water District, Point of the Mountain plant | 164 | about 9.6 |
| Jordan Valley Water Conservancy District | 184 | about 10.8 |
Where to go next
- Water softener installation in Salt Lake City
- Water heaters and hard water
- Why water heaters wear out early here
Common questions
How hard is Salt Lake City water in grains per gallon?
From about 8 grains per gallon at the Big Cottonwood plant to 12.4 at City Creek, and 9.6 to 33.4 from the city’s wells and springs, according to the 2026 water quality report.
Why is my water harder in summer?
The city blends in more groundwater from wells when mountain runoff drops, and the wells carry the highest hardness in the system.
Do I need a softener in Salt Lake City?
Not for safety. Many households install one to protect water heaters and fixtures and to cut cleaning. The softener page covers sizing.