Southern California Water Mineral Content: What’s In Your Tap?

If you live in Southern California, you’ve probably noticed signs of hard water—chalky spots on dishes, scale buildup on faucets, or dry skin after showering. These issues stem from high levels of minerals like calcium and magnesium, which naturally occur in our region’s water sources.

Hard water isn’t a health threat, but it can take a toll on your home. It clogs plumbing, shortens the lifespan of appliances, and reduces cleaning power. And nearly every city in Southern California deals with it to some degree.

Below, we break down water hardness across the region, followed by general solutions that apply to SoCal homeowners no matter where you live.

Los Angeles receives water from the Colorado River, Northern California, and local aqueducts—all rich in minerals. According to the 2023 LADWP report, water hardness in L.A. ranges from 56-220 mg/L across service zones. That classifies most of the city’s tap water as hard to very hard.

San Diego also relies heavily on imported sources like the Colorado River and the State Water Project. In 2023, water hardness levels ranged from 169-270 mg/L across various service areas, which is considered very hard. Many residents notice heavy scale buildup in water heaters and showerheads.

Water in Orange County is blended from local groundwater and imported sources. Depending on where you live, hardness can range between 99-220 mg/L. That’s firmly in the hard to very hard category.

Ontario draws most of its water from hard groundwater sources. In 2023, reported their total water hardness to average around 123 ppm, placing it below the hard category.

Escondido gets its water from local surface sources and imports. The average hardness sits around 195 mg/L. TDS and sulfate levels are also elevated, affecting both water quality and taste.

Ventura residents may receive water from the Ventura River, Lake Casitas, or local wells. Hardness levels range from 263 to 637 ppm, or 15 to 37 grains per gallon, depending on the source. Groundwater areas tend to be much harder than surface-fed ones.

Indio uses groundwater from the Coachella Valley basin. While readings vary, average hardness levels hover around 148.5 ppm as CaCO₃ (ranging from 61–240 ppm). The area consistently falls into the moderately hard to very hard range.

Hard water minerals aren’t harmful to drink, but they cause damage over time.

Over time, the costs of hard water can add up through repairs, replacements, and higher utility usage.

Across the region, common contaminants include:

While most of these contaminants are under legal limits, many exceed health-based guidelines set by organizations like the Environmental Working Group (EWG).

Water quality varies even within the same city. Different zones may draw from different sources or be affected by different infrastructure.

A home water test is the best way to find out what’s coming out of your taps. It can reveal:

Local Culligan dealers in SoCal offer free in-home water testing with fast results and no obligation.

Softening systems use ion exchange to remove calcium and magnesium. This prevents scale buildup, extends appliance life, and improves soap effectiveness.

Benefits:

For homeowners concerned about chemical contaminants, Culligan also offers:

Hard water is part of life in Southern California. From Los Angeles to Indio, homeowners deal with mineral buildup that affects everything from appliances to laundry. The good news? You can fix it.

A simple water test will show what’s in your water—and what system will help. Whether you need a softener, a filter, or both, there’s a solution for your specific needs.