Does Los Angeles Have Hard Water? LA Water Hardness by Neighborhood
Short answer: yes, and it depends on where you live. In LADWP's 2025 water quality report, Los Angeles Aqueduct water averaged 103 mg/L hardness (about 6 grains per gallon, moderately hard). Imported water from the Metropolitan Water District's Weymouth and Diemer plants averaged 234 to 236 mg/L (about 13.7 grains per gallon, very hard). Western LA mostly gets the softer aqueduct water. Eastern LA and Harbor communities are served by the harder imported water. LADWP disinfects with chloramine, not chlorine.
LA Water Hardness by Neighborhood
LADWP divides the city into water quality service areas, each fed by a different mix of sources. Hardness below is the 2025 average for the sources that serve each area, from LADWP's 2025 monitoring results. Because sources are blended, your exact tap hardness can fall anywhere in the range.
| Service Area | Example Neighborhoods | Sources (LADWP) | Typical Hardness |
|---|---|---|---|
| Western LA | Brentwood, Venice, Mar Vista, Palms, Westchester, Pacific Palisades, Century City, West LA | LA Aqueduct, MWD State Water Project | About 103 mg/L (6.0 GPG): moderately hard |
| Central LA | Hollywood, Koreatown, Mid City, Silver Lake, Los Feliz, Hancock Park, Crenshaw, Watts | LA Aqueduct, State Water Project, local groundwater | About 103 to 116 mg/L (6.0 to 6.8 GPG), individual samples up to 159: moderately hard to hard |
| San Fernando Valley | Van Nuys, Encino, Sherman Oaks, Studio City, North Hollywood, Northridge, Woodland Hills, Reseda | LA Aqueduct, local groundwater, MWD State Water Project | About 103 to 140 mg/L (6.0 to 8.2 GPG): moderately hard to hard |
| Eastern LA | Boyle Heights, Eagle Rock, Highland Park, Echo Park, El Sereno, Lincoln Heights, Atwater Village | MWD State Water Project and Colorado River water | About 140 to 236 mg/L (8.2 to 13.8 GPG), individual samples up to 280: hard to very hard |
| Harbor | San Pedro, Wilmington, Harbor City, Harbor Gateway | MWD State Water Project and Colorado River water | About 140 to 236 mg/L (8.2 to 13.8 GPG), individual samples up to 280: hard to very hard |
Neighborhood lists and sources from LADWP's service area page. LADWP notes that sources fluctuate with operational needs and supply. Classifications use the USGS scale: 61 to 120 mg/L moderately hard, 121 to 180 hard, over 180 very hard.
Hardness by Water Source (LADWP 2025)
| Source / Treatment Plant | Avg Hardness (mg/L as CaCO3) | Range | Avg GPG |
|---|---|---|---|
| Los Angeles Aqueduct Filtration Plant | 103 | 96 to 117 | 6.0 |
| Northern Combined Wells (Valley groundwater) | 115 | 78 to 151 | 6.7 |
| Southern Combined Wells | 116 | 83 to 159 | 6.8 |
| MWD Jensen Plant | 140 | 137 to 142 | 8.2 |
| MWD Weymouth Plant | 234 | 189 to 280 | 13.7 |
| MWD Diemer Plant | 236 | 191 to 280 | 13.8 |
The same report shows calcium of 27 to 30 mg/L in aqueduct and well water versus 56 mg/L in Weymouth and Diemer water, which explains most of the difference.
Where LA's Water Comes From
According to LADWP, in 2025 the city's water came from:
- Los Angeles Aqueduct: 44%. Eastern Sierra snowmelt, the softest major source.
- Metropolitan Water District (purchased): 52%. A mix of Northern California State Water Project water and Colorado River water. Colorado River water is the hardest source.
- Local groundwater: 1%.
- Recycled water: 3%.
The mix changes from year to year with snowpack and supply. In years when LA buys more MWD water, especially Colorado River water, the areas it serves get harder water.
LA Uses Chloramine: Why It Matters
LADWP has converted its system from chlorine to chloramine, made by adding ammonia to chlorine. Chloramine lasts longer in pipes and creates fewer disinfection byproducts. In LADWP's 2025 report, total chlorine residual averaged 1.7 mg/L citywide, within the state limit of 4 mg/L.
What this means for shower filters: NSF/ANSI 177, the shower filter certification, covers free chlorine, not chloramine. In independent testing, even the certified Weddell Duo did not reduce chloramine. In LA, a shower filter will do less than in a chlorine city. If your hair or skin issue is from hardness, a chelating shampoo or water softener will help more.
What LA Water Does to Hair, Skin and Appliances
Hair
Calcium and magnesium bind to the hair cuticle and make strands stiffer and rougher. In very hard Eastern LA and Harbor water, coated, dull or straw-like hair is more likely than in moderately hard Western LA water. See what the research shows about hard water and hair.
Skin
Hard water leaves more soap and surfactant residue on skin, and research links hard water to higher eczema risk in young children. LA's dry climate can make skin dryness worse. See our skin guide.
Appliances and fixtures
Expect white scale on faucets, showerheads, kettles and water heaters, especially in Eastern LA and Harbor homes. See how to remove limescale and our water heater guide.
Best Solutions by Neighborhood
| Where You Live | Renters | Homeowners |
|---|---|---|
| Western LA (moderately hard) | A chelating shampoo every week or two is usually enough | A softener is optional; descale fixtures as needed |
| Central LA and the Valley (moderately hard to hard) | Chelating shampoo; descale showerheads and kettles | Consider a water softener if scale is a problem |
| Eastern LA and Harbor (hard to very hard) | Chelating shampoo regularly; distilled or filtered final rinse for color-treated hair | A water softener is the most effective fix |
| Anywhere in LA, for drinking | A reverse osmosis system removes hardness and the chalky taste at one tap | |
Not sure which area you are in? Test your tap water with a hardness strip. It takes a minute and tells you where you fall.
Not on LADWP? Check Your Utility
This guide covers the City of Los Angeles water system run by LADWP. Many cities in LA County, including Santa Monica, Pasadena, Glendale, Burbank, Beverly Hills and Long Beach, run their own water utilities with different sources and hardness. Look at the name on your water bill, then check that utility's annual water quality report for its hardness figure.
Frequently Asked Questions About Los Angeles Water
Yes, but how hard depends on your neighborhood. In LADWP's 2025 water quality report, Los Angeles Aqueduct water averaged 103 mg/L hardness (about 6 grains per gallon, moderately hard), while imported Metropolitan Water District water from the Weymouth and Diemer plants averaged 234 to 236 mg/L (about 13.7 grains per gallon, very hard). Western LA gets mostly aqueduct water, while Eastern LA and Harbor communities are served by the harder imported water.
Based on LADWP's 2025 monitoring results, roughly 6 to 7 grains per gallon for LA Aqueduct and local well water, about 8 grains for MWD Jensen plant water, and about 13.7 grains for MWD Weymouth and Diemer plant water, with individual samples reaching about 16.4 grains per gallon.
They are served by different sources. LADWP lists Western LA communities as served by the Los Angeles Aqueduct and the State Water Project, while Eastern LA and Harbor communities are served by the State Water Project and Colorado River water from the Metropolitan Water District. The MWD Weymouth and Diemer plants averaged about 235 mg/L hardness in 2025, more than double the 103 mg/L average of LA Aqueduct water.
It changes from year to year with the source mix. In 2025, LADWP got 44 percent of its water from the Los Angeles Aqueduct and 52 percent from the Metropolitan Water District. Years with more imported MWD water, especially Colorado River water, generally mean harder water in the areas it serves.
Chloramine. LADWP has converted its system from chlorine to chloramine, which is formed by adding ammonia to chlorine. This matters for shower filters, because NSF/ANSI 177 shower filter certification covers free chlorine, not chloramine.
Yes. LADWP's 2025 report shows its water met all primary drinking water standards. Hardness is not a health concern. No PFAS were detected in LADWP's 2023 to 2024 federal UCMR5 sampling. Very hard water can taste chalky, which a reverse osmosis filter can fix.
Last updated: October 2026. Sources: LADWP 2025 monitoring results, service areas, water sources.