Los Angeles water hardness: 6 to 14 grains per gallon
Los Angeles tap water runs from about 6 to 13.8 grains per gallon (103 to 236 mg/L) on average, depending on the source. Those numbers come from LADWP's 2025 water quality monitoring results (opens in new tab).
Los Angeles water hardness
Grains per gallon, from LADWP's 2025 water quality monitoring results. Sacramento river water shown for comparison.
Where does LA water come from?
LADWP gets water from three places. The Los Angeles Aqueduct brings water from the Eastern Sierra, and it is treated at the Los Angeles Aqueduct Filtration Plant. Local wells pump groundwater from basins in the city. The rest is bought from the Metropolitan Water District, which brings water from the Colorado River Aqueduct and the State Water Project.
These sources are very different. In 2025, aqueduct water averaged about 6 grains per gallon and well water about 7. Water from MWD's Weymouth and Diemer plants averaged close to 14. The mix you get depends on your neighborhood.
What this means at home
- White scale on faucets and shower heads, worse in harder areas
- Spots on dishes and glassware
- Scale building up in water heaters
- Soap that does not rinse off cleanly
Do you need a water softener in Los Angeles?
It depends on your source. If your home gets mostly MWD water at close to 14 grains per gallon, a softener makes a big difference. If you get mostly aqueduct or well water at 6 or 7 grains per gallon, the benefit is smaller and you may be fine without one. Test your tap before you decide.
Read do I need a water softener with city water? or see what a softener costs.
Get a free water test in Los Angeles
Enter your ZIP code and we match you with a trusted local water specialist who tests your tap for free. No pressure to buy.
Book my free water testCommon questions
Is Los Angeles water hard?
It depends on where you live. LADWP's 2025 results show average hardness of 103 mg/L (about 6 grains per gallon) at the Los Angeles Aqueduct Filtration Plant and 234 to 236 mg/L (about 13.7 to 13.8 grains per gallon) for water bought from MWD's Weymouth and Diemer plants.
Why does LA water hardness vary so much?
LADWP blends water from the Los Angeles Aqueduct, local wells and the Metropolitan Water District. MWD water comes from the Colorado River Aqueduct and the State Water Project. Colorado River water is much harder than aqueduct water.
How do I find the hardness at my LA address?
LADWP's report lists results by source. To know which source serves your home, contact LADWP or test your tap. A tap test gives you your exact number.
Keep reading
DataWater hardness by cityHow hard the tap water is in US cities, from each utility report.
City dataSan Diego hard water: about 14 grains per gallonAbout 14 grains per gallon. Very hard.
GuideDo I need a water softener with city water?It depends on your city. Here is how to decide.
GuideHow much does a water softener cost installed?Installed price ranges, running costs, and what drives the price.