Your Local Guide To Water Treatment
In San Diego

Water treatment in San Diego is about more than just improving taste. Addressing local water challenges, aging infrastructure, and long-term home protection is essential for homeowners in San Diego. Whether you’re dealing with hard water, chlorine taste, or emerging contaminants like PFAS, understanding your local water quality is the first step toward choosing the right solution.

The Sweetwater Authority, which serves more than 200,000 customers in National City, Bonita, and parts of Chula Vista, confirmed that PFAS “forever chemicals” have been detected in the agency’s main reservoir. The majority of the agency’s water sources now contain toxic PFAS, and the district will soon be required to address the multimillion-dollar problem. Sweetwater Authority has started a dedicated PFAS mitigation fund expected to collect $10 million over the next eight years to cover treatment costs.

In March 2026, the authority announced renewed support for state anti-PFAS legislation aimed at holding manufacturers accountable for contamination cleanup costs. The issue is not limited to South Bay, an EWG analysis found that 177 California water systems serving over 18.9 million people detected PFAS above EPA health-protective limits between 2023 and 2025. Camp Pendleton, whose drinking water serves more than 56,000 people in northern San Diego County, continues to report elevated PFAS levels tied to legacy contamination from firefighting foam.

The San Diego County Water Authority notes that PFAS has been detected at very low levels, just above detection limits, in some of its supply sources. However, the region’s seawater desalination supplies, treated through reverse osmosis at the Carlsbad Desalination Plant, are known to effectively remove PFAS. As California tightened its drinking water notification levels for PFOA, PFOS, PFHxS, and PFHxA in October 2025, San Diego-area water agencies are facing increasing pressure to invest in advanced treatment technologies to meet new standards.

The recent San Diego Water Quality Report offers detailed insight into the composition of local drinking water. Beyond regulatory compliance, the data reveals key factors like mineral content, disinfectant levels, and trace contaminants that influence how water tastes, feels, and interacts with plumbing systems.

San Diego water measures 155–230 ppm. Hard water is not a health concern, but it can leave mineral buildup on faucets, dishes, and appliances and may make soaps and detergents less effective over time.

Measured around 1.73 ppm, chlorine is necessary for disinfection but can contribute to taste and odor issues at the tap and fuel the formation of disinfection byproducts.

Recent San Diego testing shows HAA5 (Haloacetic Acids) at about 15 ppb and TTHMs (Total Trihalomethanes) at about 49 ppb. These compounds form as a byproduct of chlorinating source water and are a common reason homeowners consider whole-house filtration.

Recent testing shows lead at ND (90th Percentile), copper at 0.6 ppm (90th Percentile), manganese at 6.1 ppb. Because lead and copper can enter water from household plumbing after it leaves the treatment plant, conditions at an individual tap can differ from system-wide averages in older homes.

While San Diego water meets regulatory standards, WQR data highlights common issues such as hardness, disinfection byproducts, and trace contaminants that can impact both health preferences and home performance.

San Diego’s housing stock is shaped by more than a century of development. Historic early-20th-century neighborhoods like Mission Hills, Bankers Hill, North Park, and South Park feature Craftsman bungalows and Spanish Colonial homes, many with original galvanized or early copper plumbing.

Large mid-century tract neighborhoods, Clairemont, Linda Vista, Allied Gardens, Serra Mesa, and the College Area, dominate the central city; homes built through the mid-1980s were plumbed with copper joined by lead-based solder, which is why utilities specifically flag this vintage for Lead and Copper Rule sampling. Post-1970s master-planned suburbs in Carmel Valley, Rancho Peñasquitos, Scripps Ranch, Mira Mesa, and Rancho Bernardo use modern copper and PEX, and Downtown, East Village, and Little Italy have added substantial high-rise multi-family stock since 2000.

North County (Carlsbad, Oceanside, Encinitas, Escondido), the South Bay (Chula Vista, National City), and East County (El Cajon, La Mesa, Santee) skew toward post-1980 single-family homes and newer master-planned communities. The defining regional feature is very hard water, 172 to 248 ppm (10.1–14.5 grains per gallon), which drives consistent demand for softening and whole-house filtration across all neighborhoods.

This combination of housing diversity and local water supply makes water treatment a localized need rather than a one-size-fits-all solution.

Water quality in San Diego is shaped by the scale and complexity of its infrastructure. Serving Around 3.3 million, the local system must deliver water across a wide mix of neighborhoods, each with different demands on the system.

mported water makes up 80–90% of supply (blend from Colorado River + State Water Project via SDCWA, plus <10% treated water from MWD Skinner, Twin Oaks Valley, and Carlsbad Desalination). Local supply is growing via Pure Water San Diego Phase 1 (>70% complete).

The City of San Diego Public Utilities Department operates three municipal water treatment plants, Alvarado, Miramar, and Otay, that serve interconnected distribution zones across the city, providing redundancy so customers can be supplied from more than one plant when needed. Alvarado and Miramar use ozone for primary disinfection, while Otay uses chlorine dioxide; all three employ conventional treatment (coagulation, flocculation, sedimentation, and sand/multimedia filtration) to meet federal and state standards. Chloramines are used for residual disinfection in the distribution system (2024 average 1.73 ppm). The department completed a system-wide Water Service Line Inventory and confirmed no lead service lines anywhere in the system. The City also captured and stored 19.5 billion gallons of local runoff, enough to supply its 1.4 million customers for approximately 130 days, as part of its ongoing shift toward more locally controlled supply through the Pure Water San Diego program.

The City of San Diego Public Utilities Department operates one of the largest municipal water systems on the West Coast, delivering drinking water to approximately 1.4 million customers within the City of San Diego; Culligan San Diego’s broader service territory covers roughly 3.3 million residents across the San Diego metropolitan area.

The City treats water at three municipal plants, Alvarado, Miramar, and Otay, and supplements its own supply with purchased treated water from the Metropolitan Water District’s Skinner plant, the San Diego County Water Authority’s Twin Oaks Valley plant, and the Carlsbad Desalination Plant. The department recorded zero primary drinking water standard violations and is recognized by the American Water Works Association’s Partnership for Safe Water program (Otay, Director’s Award, 16 consecutive years; Miramar, Director’s and President’s Awards, 11 consecutive years; Alvarado, PSW Director’s Award in 2024). Customer satisfaction is high, with 85% of customers reporting they are satisfied or very satisfied with the Department’s level of service, and recent operational improvements have driven a 92% drop in customer call wait times and a 90% reduction in the held bill backlog.

Culligan San Diego serves customers across a wide regional service area, including:

As a result, even though the overall system meets regulatory standards, water can behave differently from one home to the next. In this environment, water treatment becomes less about meeting baseline safety requirements and more about optimizing your home’s water based on your local area.

Water treatment systems are designed to address the most common issues identified in San Diego water quality reports.

Water softeners remove hardness minerals like calcium and magnesium to prevent scale buildup and improve efficiency.

Whole house water filters reduce chlorine, sediment, and chemical contaminants throughout the entire home.

Reverse osmosis systems provide advanced drinking water filtration, removing contaminants like lead, and disinfection byproducts at the point of use.

Targets emerging contaminants like PFAS at extremely low levels for long-term protection.

Many homeowners choose water treatment solutions to address:

In addition to choosing the right system, San Diego homeowners have flexible options when it comes to installation, maintenance, and ongoing service. Culligan San Diego offers both rental and installation solutions, allowing homeowners to choose what best fits their needs and budget.Learn more about Culligan San Diego.

Because water quality varies across San Diego neighborhoods, the best first step is a professional water test. This helps identify the exact issues in your home and ensures the right system is selected based on your water conditions. Schedule your free water test here.