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WaterSafeCheck
Official EPA SDWIS Verified ReportWater Quality & Testing GuideStatus: Normal Operations

ZIP Code 91935 Water Quality & Testing Report

Jamul, CA · San Diego County County · Updated for 2026

Quick EPA Verified Answer

Is Tap Water Safe to Drink in ZIP 91935 (Jamul, CA)?

Caution / Filtration Recommended: Tap water in ZIP code 91935 (Jamul, CA) has compliance concerns, earning an EPA Safety Grade of C (69/100) due to 6 health violation(s) and 4.0 ppb lead. While treated by OTAY WATER DISTRICT, residents are advised to use an NSF/ANSI 53 certified water filter for drinking and cooking.

Safety Score
C

Water Safety Grade

Fair — Some compliance concerns

Health Violations

6

Total Violations

10

Lead Risk

Moderate

Contaminants

2

⚠

Active Water Quality Issues Detected

EPA records show 7 unresolved violations. Contact OTAY WATER DISTRICT for current status.

About Tap Water in ZIP Code 91935

Tap water in ZIP code 91935 (Jamul, CA) is distributed by OTAY WATER DISTRICT (EPA ID: CA3710034), serving approximately 238,008 residents. Based on EPA Safe Drinking Water Act compliance records, this system receives a water safety grade of C with a composite quality score of 69/100.

Water System

OTAY WATER DISTRICT

EPA ID: CA3710034

Water Source

Surface Water

Population Served

238,008 residents

County

San Diego County County, California

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Lead Levels in ZIP 91935

EPA action level: 15 ppb | Public health goal: 0 ppb

Lead Level: 4.0 ppb — Very Low

The 90th percentile lead level in 91935 is 4.0 ppb. This meets the EPA action level of 15 ppb. Health experts recommend a target of 0 ppb for optimal safety.

Lead exposure risk in 91935 is rated Moderate. EPA models estimate a 45% exposure probability based on housing and infrastructure age.

Lead Level (90th percentile)
4.00 ppb (0.004 mg/L)
Lead Exposure Risk Rating
Moderate
Lead Exposure Probability

EPA model estimate based on housing age and infrastructure

45%
Note: Lead levels above are the 90th percentile from EPA monitoring — meaning 90% of samples were at or below this level. Even "undetected" tap water lead doesn't account for lead leaching from home plumbing. If your home was built before 1986, individual tap testing is recommended.
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Water Hardness & Mineral Content

Grains per gallon (GPG) & Parts per million (PPM / mg/L)

Classification: Hard7.2 GPG · 123 mg/L

Water in ZIP 91935 is Hard (123 mg/L / 7.2 GPG). Residents may notice white mineral spots on glassware, reduced soap efficiency, and mineral scale on faucets and showerheads.

Recommendation: An ion-exchange water softener or descaler is recommended to prolong the life of water heaters, dishwashers, and plumbing.
Hardness (GPG)

Grains per gallon

7.2 GPG
Hardness (PPM / mg/L)

Parts per million CaCO3

123 mg/L
Appliance Scaling Risk
High / Severe

Official EPA SDWIS Database Entry

Utility: OTAY WATER DISTRICT · PWSID: CA3710034

Verify on EPA.gov
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Violation History

Past 5 years — EPA SDWIS data

OTAY WATER DISTRICT has recorded 6 health-based violations out of 10 total violations over the past 5 years. 7 violations remain unresolved in EPA tracking records.

Total Violations (5 yr)
10
Health-Based Violations
6
Unresolved Violations
7
Boil Water Advisories
0
Compliance Risk
Critical

Regulatory compliance risk for this utility is rated Critical based on past reporting and enforcement records.

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Contaminants Detected

Contaminants with health-based violations on record

EPA records identify 2 contaminants with health-based violations in the past 5 years: Contaminant 4109, Combined Radium.

Contaminant 4109Combined Radium

⚖ Enforcement Actions

EPA or state regulators have issued 9 enforcement actions to address compliance lapses.
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Water Source & Environmental Factors

Surface Water

This system draws water from lakes, rivers, or reservoirs. Surface water is treated to remove sediment, microorganisms, and chemical contaminants before reaching taps.

Water Source Type
Surface Water
EPA Radon Zone

Lower potential

Zone 3
Energy Burden

% of household income spent on energy — indicator of older infrastructure

2.62%

EPA Radon Zone 3 — lower radon potential, though the EPA still recommends testing all homes.

Water Quality Testing in ZIP 91935

Tap Water & Well Testing Recommendations

Residents in ZIP code 91935 served by OTAY WATER DISTRICT can test tap water or private well systems to verify water purity. Testing detects hidden contaminants before they impact family health.

Tap Water Testing Steps

  • 1.Conduct a certified lead check if your home was constructed before 1986.
  • 2.Use certified lab testing kits rather than uncalibrated test strips for regulated compliance.
  • 3.Sample water from both your kitchen faucet and water heater to compare line purity.

Private Well Testing Steps

  • •Test for Coliform bacteria and Nitrates annually.
  • •Test for heavy metals, radon, and PFAS every 3 years.
  • •Send samples to a state-certified drinking water laboratory recognized by California State Water Resources Control Board.
Certified Lab Testing: Always use an EPA-certified drinking water laboratory in CA for formal legal or real estate compliance testing.

🛡 What Should You Do? — ZIP 91935 Recommendations

  • ⚠ Use a certified NSF/ANSI 53 filter for drinking and cooking water if you have young children
  • ⚠ Never give unfiltered tap water to infants in formula — use certified bottled or filtered water
  • ⚠ Request a copy of the Consumer Confidence Report to see what was detected and when
  • ⚠ Call the EPA Safe Drinking Water Hotline: 1-800-426-4791

Recommended Water Treatment Systems:

🏺

NSF 53 Lead Pitcher Filter

Specifically certified to reduce lead and copper at the tap.

Lead Filter Guide →
⚗️

NSF 58 Under-Sink RO System

Advanced filtration for PFAS, fluoride, nitrates, and organic chemicals.

RO System Guide →

Frequently Asked Questions — ZIP 91935 Water Quality

Is tap water safe to drink in ZIP code 91935?+
Tap water in 91935 (Jamul, CA) meets major standards but has a grade of C due to minor past violations. Vulnerable populations may want to use a certified filter as a precaution.
How do I get my water tested in ZIP 91935 (Jamul, CA)?+
To test water quality in ZIP 91935, you can order a certified drinking water test kit or send water samples to an EPA/NELAP certified laboratory in CA. Certified testing checks for lead, coliform bacteria, nitrates, hardness, and PFAS that standard test strips miss. Contact California State Water Resources Control Board for a list of certified regional labs.
How hard is the tap water in 91935?+
Tap water in 91935 is classified as Hard with an estimated mineral hardness of 123 mg/L (7.2 GPG). An ion-exchange water softener or descaler is recommended to prolong the life of water heaters, dishwashers, and plumbing.
Should I test private well water in 91935?+
Yes. Unlike municipal systems, private wells in 91935 are not regulated by the EPA or local utilities. Private well owners should test their water annually for coliform bacteria and nitrates, and every 3 to 5 years for heavy metals (lead, arsenic) and volatile organic compounds.
What is the lead level in 91935 tap water?+
The 90th percentile lead level in 91935 is 4.0 ppb. The EPA action level is 15 ppb. This is below the EPA action level.
Is there an active boil water notice in 91935?+
There are currently no active boil water advisories on record for 91935. Water treatment systems are operating within normal parameters.
Who provides tap water to 91935?+
Tap water in ZIP code 91935 is provided by OTAY WATER DISTRICT (EPA ID: CA3710034), serving approximately 238,008 residents.
What water filter should I use in 91935?+
Based on water metrics for 91935, we recommend Reverse Osmosis (PFAS & Lead). Look for certifications such as NSF/ANSI 53 (Chemical Contaminants), NSF/ANSI 42 (Aesthetic Effects).

Data Sources & Methodology

Water quality data for ZIP code 91935 is compiled from the EPA Safe Drinking Water Information System (SDWIS), EPA ECHO enforcement database, UCMR5 unregulated contaminant monitoring, and Consumer Confidence Reports filed by OTAY WATER DISTRICT. Safety scores are composite metrics derived from violation history, lead levels, enforcement actions, and infrastructure risk indicators. Data reflects a 5-year monitoring window. Last dataset update: 2024. View EPA source data →