National City, California Water Quality Report

Comprehensive water safety analysis • Updated February 2026

National City's water quality score of 69/100 falls below average, with 2 contaminants at concerning levels.

All 3 historical violation(s) in National City have been resolved.

Water Safety Overview

Some Concerns. Consider a water filter for extra protection. Score: 69/100.

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8
Total Tested
0
Above EPA Limit
2
Elevated
6
Safe Levels

Contaminants at Elevated Levels

Above 50% of EPA limits

ContaminantLevel DetectedEPA Limit% of LimitStatus
Total Trihalomethanes
54.87 ug/L
80.00 ug/L
68.6%
Warning
Haloacetic Acids
30.31 ug/L
60.00 ug/L
50.5%
Warning

All Detected Contaminants

8 contaminants tested • EPA SDWIS data

ContaminantLevel DetectedEPA Limit% of LimitStatus
Total Trihalomethanes
54.87 ug/L
80.00 ug/L
68.6%
Warning
Haloacetic Acids
30.31 ug/L
60.00 ug/L
50.5%
Warning
Chromium
0.042 mg/L
0.100 mg/L
42.2%
Safe
Nitrate
2.85 mg/L
10.00 mg/L
28.5%
Safe
Mercury
0.0006 mg/L
0.0020 mg/L
28.4%
Safe
Lead
0.0042 mg/L
0.015 mg/L
28.2%
Safe
Copper
0.355 mg/L
1.30 mg/L
27.3%
Safe
Arsenic
0.0019 mg/L
0.010 mg/L
18.5%
Safe

Detailed Water Quality Analysis for National City

In-depth assessment of your municipal water supply

The water quality in National City, California has been comprehensively evaluated using data from the EPA's Safe Drinking Water Information System (SDWIS) and local water utility reports. Our analysis examines 8 distinct contaminants across multiple categories including inorganic chemicals, disinfection byproducts, microorganisms, and radionuclides. With an overall quality score of 69 out of 100 (Grade: C+), National City's water supply meets minimum EPA requirements but shows areas for improvement.

Water Source and Treatment

National City's primary water system, NATIONAL CITY WATER SYSTEM, serves approximately 58,660 residents. The water is sourced from surface water sources such as rivers, lakes, or reservoirs. Surface water typically requires more extensive treatment including coagulation, sedimentation, filtration, and disinfection to remove sediments, organic matter, and pathogens.

Contaminant Profile Overview

Of the 8 contaminants analyzed in National City's water supply, 6 (75%) are present at safe levels below 50% of EPA Maximum Contaminant Levels (MCLs). 2 contaminants are detected at elevated levels between 50-100% of MCLs, warranting monitoring. No contaminants currently exceed EPA safety limits. The most common categories of concern in municipal water supplies include disinfection byproducts formed during the chlorination process, heavy metals like lead that can leach from aging infrastructure, and naturally occurring contaminants like arsenic or radium that vary by geographic region.

Regulatory Compliance Status

National City's water system has a compliance history with 3 documented EPA violations. All historical violations have been addressed and resolved. Violations can range from monitoring and reporting failures to actual exceedances of contaminant limits. Water utilities are required by law to notify customers of any violations that may affect health and to take corrective action to return to compliance.

Infrastructure Considerations

Water quality at the tap can differ from quality at the treatment plant due to distribution system conditions. Homes built before 1986 may have lead service lines or lead solder in plumbing that can contribute to lead exposure. Older galvanized pipes can harbor bacteria and release metals. Running cold water for 30 seconds to 2 minutes before drinking or cooking helps flush stagnant water from pipes. Residents in older homes should consider testing their water directly at the tap to assess any additional contamination from household plumbing, as EPA monitoring typically occurs at distribution points rather than individual residences.

Health Implications of National City Water Quality

Understanding potential health effects for residents

Vulnerable Populations

Certain groups face elevated health risks from water contaminants and should take extra precautions. Pregnant women are particularly vulnerable as contaminants like lead and nitrates can affect fetal development, potentially causing developmental delays and birth defects. Infants and young children are at heightened risk because their developing bodies absorb contaminants more readily and are more susceptible to their effects; lead exposure in children can cause irreversible cognitive impairment and behavioral problems. Elderly individuals and those with compromised immune systems (including cancer patients, organ transplant recipients, and HIV/AIDS patients) are more susceptible to waterborne pathogens and may experience severe illness from microorganisms that healthy adults can tolerate. Individuals with kidney disease should be aware of fluoride and other mineral levels, as impaired kidney function affects the body's ability to filter these substances.

Lead Health Effects

Lead has been detected in National City's water supply. There is no safe level of lead exposure. In children, lead can cause developmental delays, learning difficulties, irritability, weight loss, hearing loss, and seizures. In adults, lead exposure contributes to cardiovascular problems, decreased kidney function, and reproductive issues. Pregnant women exposed to lead can transfer it to their developing fetus, increasing risk of premature birth and reduced growth. Use an NSF 53 certified filter and run cold water before drinking to reduce exposure.

Arsenic Health Effects

Arsenic has been detected in National City's water supply. Long-term arsenic exposure, even at levels near EPA limits, is associated with increased risk of skin, lung, bladder, kidney, and liver cancers. Arsenic exposure can also cause cardiovascular disease, diabetes, and neurological effects. Skin changes like thickening and pigmentation may indicate chronic exposure. Reverse osmosis filtration is highly effective at removing arsenic from drinking water.

Nitrate Health Effects

Elevated nitrate levels in National City's water pose particular risk to infants under six months. Nitrates can cause methemoglobinemia ("blue baby syndrome"), a condition where the blood cannot carry sufficient oxygen. Symptoms include bluish skin color, shortness of breath, and in severe cases, death. Formula-fed infants are at greatest risk. Pregnant women should also limit nitrate exposure. Boiling water does NOT remove nitrates—it actually concentrates them. Reverse osmosis or distillation systems effectively remove nitrates.

General Recommendations

Based on National City's water quality profile, residents should consider the following protective measures: Installing a point-of-use water filter is strongly recommended given the current water quality score. Always use cold water for drinking and cooking, as hot water can contain higher levels of metals from pipes. Have your home tested if it was built before 1986 to check for lead plumbing. Review your annual Consumer Confidence Report (water quality report) from your utility to stay informed about local water quality trends. Pregnant women, families with young children, and immunocompromised individuals should consult healthcare providers about water safety precautions specific to their situation.

Recommended Water Filters for National City

Based on detected contaminants

Reverse Osmosis System

Best for National City. Removes 95-99% of contaminants including heavy metals, PFAS, and nitrates.

  • ✓ Removes lead
  • ✓ Removes arsenic
  • ✓ Removes nitrates
  • ✓ Removes total dissolved solids

Activated Carbon Filter

Good for National City. Removes chlorine, improves taste, and filters many organic compounds.

  • ✓ Removes chlorine and chloramine
  • ✓ Improves taste and odor
  • ✓ Filters pesticides and VOCs

NSF 53 Lead Certification Required

Lead detected in National City. Ensure any filter is NSF/ANSI 53 certified for lead removal.

EPA Compliance History

Past violations for National City's water system

MCL

Chromium - 2/4/2021

Resolved

reporting

Copper - 2/4/2024

Resolved

monitoring

Chromium - 2/4/2024

Resolved

Water System Information

NATIONAL CITY WATER SYSTEM

PWS ID:
CA423263
Population Served:
58,660
Water Source:
surface
C+69/100

National City Water Quality Score

Based on EPA contaminant data and compliance records

69
Contaminants
72
Compliance
69
Infrastructure

Areas of Concern

  • Aging infrastructure may affect water quality

Positive Findings

  • Water quality needs improvement

Protect Your Family's Water

National City's water contains Total Trihalomethanes at 69% of the EPA limit. A quality water filter can reduce this contaminant.

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