Data & Methodology — Kings County

Full contaminant data, sample history, and sourcing for Kings County. For readers who want to go beyond the summary.

Contaminant Data — All Analytes

361 well testing events on record, covering 25 analytes. Data spans 1929 to 2022.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. CA Avg
Manganese 195 1979–2021 94%
209% of limit ↓ 32% below
Sulfate 334 1929–2021 99%
88% of limit ↑ 335% above
Arsenic 188 1984–2021 90%
80% of limit ↑ 105% above
Uranium 120 1989–2021 98%
23% of limit ↑ 324% above
Iron 214 1959–2021 91%
23% of limit ↓ 82% below
Chloride 322 1929–2021 100%
29% of limit ~ typical
Nitrate 265 1946–2021 73%
9% of limit ↓ 63% below
Boron 21 2015–2020 100%
23% of limit ↑ 39% above
Radon 8 1995–2014 100%
10% of limit ↓ 89% below
1,2,3-Trichloropropane 21 2015–2020 5%
3620% of limit ↑ 152% above
Nitrite 177 1984–2021 53%
2% of limit ↑ 103% above
Fluoride 244 1951–2021 98%
12% of limit ↑ 80% above
PFNA municipal 41 2019–2025 0%
— —
Chromium (total) 21 2015–2020 24%
0% of limit ↓ 81% below
PFOS municipal 41 2019–2025 0%
— —
HFPO-DA (GenX) municipal 41 2019–2025 0%
— —
Perchlorate 21 2015–2020 24%
5% of limit ↓ 28% below
PFOA municipal 41 2019–2025 0%
— —
Lead 113 1984–2021 41%
8% of limit ~ typical
PFHxS municipal 41 2019–2025 0%
— —
Tds 21 2015–2020 100%
— ~ typical
Hardness 333 1929–2021 100%
— ↓ 45% below
Sodium 334 1929–2021 100%
— ↑ 167% above
PFBS municipal 41 2019–2025 0%
— —
pH 338 1951–2021 100%
— ~ typical

Distribution shows the share of samples in each concentration band relative to the EPA Maximum Contaminant Level (MCL): Low = below half the MCL, Moderate = between half and the MCL, High = above the MCL. Analytes without an MCL (e.g. sodium, pH) show — in the limit columns. State average is based on county median values across CA.

Compare your result with Kings County

Of the 188 arsenic tests on record for Kings County (1984–2021), 10% found none, and half were below 7 µg/L.

Of the 322 chloride tests on record for Kings County (1929–2021), 0% found none, and half were below 72 mg/L.

Of the 21 chromium (total) tests on record for Kings County (2015–2020), 76% found none.

Of the 244 fluoride tests on record for Kings County (1951–2021), 2% found none, and half were below 500 µg/L.

Of the 214 iron tests on record for Kings County (1959–2021), 9% found none, and half were below 52.5 µg/L.

Of the 113 lead tests on record for Kings County (1984–2021), 59% found none.

Of the 195 manganese tests on record for Kings County (1979–2021), 6% found none, and half were below 84.3 µg/L.

Of the 265 nitrate tests on record for Kings County (1946–2021), 27% found none, and half were below 294 µg/L.

Of the 334 sulfate tests on record for Kings County (1929–2021), 1% found none, and half were below 215 mg/L.

Of the 21 tds tests on record for Kings County (2015–2020), 0% found none, and half were below 429 mg/L.

Of the 120 uranium tests on record for Kings County (1989–2021), 2% found none, and half were below 6.68 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 195 samples
  • Sulfate 334 samples
  • Arsenic 188 samples
  • Uranium 120 samples
  • Iron 214 samples
  • Chloride 322 samples
  • Nitrate 265 samples
  • Boron 21 samples
  • 1,2,3-Trichloropropane 21 samples
  • Nitrite 177 samples
  • Fluoride 244 samples
  • PFNA 41 samples
  • Chromium (total) 21 samples
  • PFOS 41 samples
  • HFPO-DA (GenX) 41 samples
  • Perchlorate 21 samples
  • PFOA 41 samples
  • Lead 113 samples
  • PFHxS 41 samples
  • Tds 21 samples
  • Hardness 333 samples
  • Sodium 334 samples
  • PFBS 41 samples
  • pH 338 samples

Limited data (<15 samples) — interpret with caution

  • Radon 8 samples

Public vs. Private Water in Kings County

43 Active public water systems
155,929 Residents on public water
5% Households on private wells

Public water systems in Kings County are regulated by the EPA and must test and report contaminant levels. Private well owners are responsible for their own testing — there is no routine monitoring of private wells by any government agency.

CDC Health Outcome Correlations

Where contaminants detected in Kings County have established associations with specific health outcomes, we cross-reference CDC PLACES county-level prevalence data. This is a contextual signal, not a causal claim.

Contaminant Associated Condition Kings County Prevalence CA Average Source Year
Arsenic Cancer prevalence 5.1% 6.2% 2020
Arsenic Kidney disease rate 3.2% 3.0% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Kings County CDC PLACES data →

Data Sources

This report aggregates data from the following public databases:

Methodology

Raw records are downloaded from the Water Quality Portal and normalized to µg/L (ppb). Records are deduplicated by sample ID and date, and certified outliers are excluded. Analyte names are mapped to EPA canonical forms. Detection rates, distribution bands, and MCL comparisons are computed from the normalized dataset.

Distribution bands use the EPA Maximum Contaminant Level as the threshold: concentrations below 50% of the MCL are classed as Low, between 50% and 100% as Moderate, and above 100% as High. For analytes without an MCL (sodium, hardness, pH), distribution is not computed.

State comparison uses the median of county median values across all counties in CA with at least one sample for that analyte.

Last updated: 2026-09-10

Full methodology →