Drinking water quality · 2024
· Verified
What's in Pomona, CA tap water
68 contaminants were measured in the Pomona, CA water system's 2024 annual report. Each is shown below against its federal limit — 3 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 68
- Over federal limit
- 3
- Approaching the limit
- 0
- Worst contaminant
- PFOS
- Service area
- CA
4.5× the limit
state-level CCR
PFAS — EPA UCMR5 (2023–2025)
2 PFAS compounds above EPA limits in Pomona, CA
The EPA finalized the first-ever federal drinking-water limits for six PFAS compounds in April 2024. These numbers come straight from EPA's UCMR5 lab dataset — every U.S. system serving more than 3,300 people tested every PFAS sample at an entry point to its distribution system. PFAS not listed below were either tested and not detected, or not yet sampled.
PFOS (Perfluorooctane sulfonic acid)
● Over EPA limit (4.5×)Measured 18 ng/LEPA limit 4 ng/LSample year 2024Samples 1 detect / 15
PFOA (Perfluorooctanoic acid)
● Over EPA limit (1.8×)Measured 7.1 ng/LEPA limit 4 ng/LSample year 2024Samples 1 detect / 15
PFHxS (Perfluorohexane sulfonic acid)
● Below limitMeasured 7.9 ng/LEPA limit 10 ng/LSample year 2024Samples 1 detect / 15
PFPeA
● Detected (no federal limit)Measured 4.4 ng/LSample year 2024Samples 1 detect / 15
PFBS
● Detected (no federal limit)Measured 3.2 ng/LSample year 2024Samples 1 detect / 15
PFHxA
● Detected (no federal limit)Measured 4.1 ng/LSample year 2024Samples 1 detect / 15
PWSID CA1910126 · Source: EPA UCMR5. Limits per EPA's April 2024 PFAS National Primary Drinking Water Regulation. PFAS values reported in nanograms per liter (ng/L) — note that 1 ng/L = 1 part per trillion.
Where your water comes from · EPA SDWIS
Pomona, CA's drinking water comes from ground water, drawn from 23 sources.
Source
23ground water
- WELL · 18
- TUNNEL · 4
- PEDLEY FILTRATION PLANT - RAW
Treatment
18treatment plants
- WELL 03 AIR STRIPPER
- PEDLEY FILTRATION PLANT - TREATED
- ANION EXCHANGE PLANT - 3
- + 15 more
Distribution
22storage units
Also buys water from METROPOLITAN WATER DIST. OF SO. CAL., THREE VALLEYS MWD.
Source: EPA SDWIS facilities inventory. Methodology.
Compliance history
Federal Safe Drinking Water Act violation & enforcement records (EPA SDWIS). A violation is a regulatory determination by the state or EPA — separate from the measured levels above.
- Treatment technique violationHealth-based1 violation on record · most recent Jun 1993resolved
Source: EPA SDWIS / ECHO. View the full federal record on EPA ECHO ↗
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TurbidityA measure of cloudiness from suspended particles in the water. | 0–1.3 NTURangePomona Groundwater | 1 NTUMCL | At or above the limit |
+By source (9)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +6 more
| |||
| AlkalinityA measure of the water's capacity to neutralize acids. | 140–200 mg/LRangePomona Effluent | None set | Detected — no federal limit |
+By source (7)— Pomona Effluent, Pomona Groundwater, Miramar Groundwater Well #1 +4 more
| |||
| ColorA measure of visible tint in the water. | 1Reported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Pomona Effluent +4 more
| |||
| HardnessA measure of dissolved calcium and magnesium minerals. | 150–310 mg/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (7)— Pomona Groundwater, Weymouth Effluent, Miramar Groundwater Well #2 +4 more
| |||
| OdorA measure of detectable smell in the water. | 1Reported levelMiramar Effluent | None set | Detected — no federal limit |
+By source (7)— Miramar Effluent, Miramar Groundwater Well #1, Miramar Groundwater Well #2 +4 more
| |||
| pHA measure of how acidic or basic the water is. | 6.64–8.37Reported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (8)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +5 more
| |||
| Specific ConductanceA measure of how well water conducts electricity, which tracks dissolved mineral content. | 912–1080Reported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Groundwater Grand Well +4 more
| |||
| TOCTotal organic carbon — a measure of organic material dissolved in the water. | 0.52–3.3 mg/LReported levelPomona Effluent | None set | Detected — no federal limit |
+By source (3)— Pomona Effluent, Weymouth Effluent, Miramar Effluent
| |||
| Total Dissolved SolidsTotal dissolved solids — the combined content of all dissolved minerals and salts. | 573–690 mg/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Groundwater Grand Well +4 more
| |||
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| NitrateA compound from fertilizer runoff, septic systems, and erosion of natural deposits. | 0–7 mg/LRangePomona Groundwater | 10 mg/LMCL | Within the limit |
+By source (8)— Pomona Groundwater, Miramar Groundwater Miragrand Well, Miramar Groundwater Well #1 +5 more
| |||
| FluorideA mineral often added to drinking water to help prevent tooth decay. | 0.3–0.8 mg/LRangeWeymouth Effluent | 4 mg/LMCL | Within the limit |
+By source (7)— Weymouth Effluent, Miramar Groundwater Well #1, Miramar Groundwater Well #2 +4 more
| |||
| Asbestos | Not detected MFLRangePomona Groundwater | 7 MFLMCL | None detected |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| Cyanide | Not detected ug/LRangePomona Groundwater | None set | None detected |
+By source (7)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +4 more
| |||
| NitriteA compound from fertilizer runoff, sewage, and erosion of natural deposits. | Not detected mg/LRangeWeymouth Effluent | 1 mg/LMCL | None detected |
+By source (6)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +3 more
| |||
| ChlorideA naturally occurring salt compound. | 8.7–130 mg/LReported levelPomona Groundwater | None set | Detected — no federal limit |
+By source (7)— Pomona Groundwater, Weymouth Effluent, Miramar Effluent +4 more
| |||
| SulfateA naturally occurring mineral from rock and soil. | 200–250 mg/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Effluent +4 more
| |||
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | 0–8.6 pCi/LReported levelPOMONA GROUNDWATER (Domestic Water) | 15 pCi/LMCL | Within the limit |
+By source (6)— POMONA GROUNDWATER (Domestic Water), Pomona Effluent, Weymouth Effluent +3 more
| |||
| Combined RadiumCombined radium-226 and radium-228 — naturally occurring radioactive elements. | 0–1.63 pCi/LReported levelPOMONA GROUNDWATER (Domestic Water) | 5 pCi/LMCL | Within the limit |
+By source (5)— POMONA GROUNDWATER (Domestic Water), Miramar Groundwater Miragrand Well, Miramar Effluent +2 more
| |||
| Gross Beta Particle ActivityGross beta particle activity — a combined measure of beta-emitting radioactive substances. | 0–5 pCi/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (2)— Weymouth Effluent, Miramar Effluent
| |||
| UraniumA naturally occurring radioactive metal from erosion of natural deposits. | 0–5.9 pCi/LReported levelPOMONA GROUNDWATER (Domestic Water) | 20 pCi/LMCL | Detected — no federal limit |
+By source (6)— POMONA GROUNDWATER (Domestic Water), Miramar Groundwater Miragrand Well, Weymouth Effluent +3 more
| |||
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TrichloroethyleneAn industrial solvent (TCE) used in metal degreasing. | 0–2.7 ug/LRangePomona Groundwater | 5 ug/LMCL | Within the limit |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| TetrachloroethyleneAn industrial solvent (PCE) used in dry cleaning and degreasing. | 0–2 ug/LRangePomona Groundwater | 5 ug/LMCL | Within the limit |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| DBCP1,2-dibromo-3-chloropropane — a banned soil fumigant pesticide. | 0–49 ng/LRangePomona Groundwater | None set | Within the limit |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| 1,2,3-TCP | Not detected ng/LReported levelMiramar Groundwater Well #1 | None set | None detected |
+By source (8)— Miramar Groundwater Well #1, Miramar Groundwater Well #2, Miramar Groundwater Grand Well +5 more
| |||
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TTHMTotal trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. | 0–30 ug/LRangePomona Groundwater | None set | Within the limit |
+By source (2)— Pomona Groundwater, Pomona Effluent
| |||
| BromateA disinfection byproduct formed when bromide-containing water is treated with ozone. | 2 ug/LReported levelWeymouth Effluent | None set | Within the limit |
| NDMA | Not detected ng/LReported levelMiramar Effluent | 10 ng/LNL | None detected |
+By source (3)— Miramar Effluent, Pomona Groundwater, Weymouth Effluent
| |||
| BromodichloromethaneA trihalomethane disinfection byproduct. | 0–7.1 ug/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (2)— Pomona Groundwater, Pomona Effluent
| |||
| BromoformA trihalomethane disinfection byproduct. | 0–7.7 ug/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (2)— Pomona Groundwater, Pomona Effluent
| |||
| ChlorateA byproduct that can form during disinfection, especially when hypochlorite solutions degrade. | 80 ug/LReported levelWeymouth Effluent | 800 ug/LNL | Detected — no federal limit |
+By source (5)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +2 more
| |||
| ChloroformA trihalomethane formed when chlorine reacts with organic matter in water. | 0–11 ug/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (2)— Pomona Groundwater, Pomona Effluent
| |||
| DibromochloromethaneA trihalomethane disinfection byproduct. | 0–10 ug/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (2)— Pomona Groundwater, Pomona Effluent
| |||
| PerchlorateA chemical used in rocket fuel and fireworks that can also form during disinfection. | 0–3.5 ug/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (7)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +4 more
| |||
Other
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Dichloroethylene 11 | 0–1.5 ug/LRangePomona Groundwater | None set | Within the limit |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| Chromium | 0–15 ug/LRangePomona Groundwater | None set | Within the limit |
+By source (7)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +4 more
| |||
| Trichloroethane 111 | Not detected ug/LRangeWeymouth Effluent | None set | None detected |
+By source (8)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +5 more
| |||
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| CopperA metal that enters water from corroding household plumbing. | 0.18 mg/L90th percentileConsumers' Taps | 1.3 mg/LAction level | Within the limit |
+By source (8)— Consumers' Taps, Pomona Groundwater, Pomona Effluent +5 more
| |||
| BariumA metal from erosion of natural deposits and industrial discharge. | 124 ug/LRangeWeymouth Effluent | None set | Within the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Pomona Effluent +4 more
| |||
| ArsenicA naturally occurring element that also enters water from industry and agriculture. | Not detected ug/LReported levelMiramar Groundwater Well #2 | None set | None detected |
+By source (7)— Miramar Groundwater Well #2, Miramar Groundwater Grand Well, Miramar Effluent +4 more
| |||
| IronA naturally occurring metal common in groundwater. | Not detected ug/LReported levelPomona Groundwater | None set | None detected |
+By source (7)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +4 more
| |||
| LeadA toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. | 0 ug/L90th percentileConsumers' Taps | None set | None detected |
+By source (8)— Consumers' Taps, Pomona Groundwater, Pomona Effluent +5 more
| |||
| ManganeseA naturally occurring metal from soil and rock. | Not detected ug/LReported levelPomona Groundwater | None set | None detected |
+By source (7)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +4 more
| |||
| Strontium | Not detected pCi/LReported levelWeymouth Effluent | None set | None detected |
+By source (2)— Weymouth Effluent, Miramar Effluent
| |||
| ZincA naturally occurring metal that can also enter water from corroding pipes. | Not detected mg/LReported levelWeymouth Effluent | None set | None detected |
+By source (7)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +4 more
| |||
| AluminumA common element sometimes used as a treatment coagulant. | 0–150 ug/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (6)— Weymouth Effluent, Pomona Groundwater, Miramar Effluent +3 more
| |||
| BoronA naturally occurring element from rock and soil. | 140 ug/LReported levelWeymouth Effluent | 1 ug/LNL | Detected — no federal limit |
+By source (5)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +2 more
| |||
| CalciumA naturally occurring mineral that contributes to water hardness. | 49–92 mg/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (7)— Pomona Groundwater, Weymouth Effluent, Miramar Groundwater Grand Well +4 more
| |||
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0–12 ug/LRangePomona Groundwater | None set | Detected — no federal limit |
+By source (8)— Pomona Groundwater, Miramar Groundwater Miragrand Well, Miramar Groundwater Well #1 +5 more
| |||
| LithiumA naturally occurring element found in some groundwater. | 32–47 ug/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (5)— Weymouth Effluent, Miramar Groundwater Well #2, Miramar Groundwater Grand Well +2 more
| |||
| MagnesiumA naturally occurring mineral that contributes to water hardness. | 25–29 mg/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Pomona Effluent +4 more
| |||
| PotassiumA naturally occurring mineral from rock and soil. | 4.6–5.4 mg/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Effluent +4 more
| |||
| SodiumA naturally occurring salt component. | 93–117 mg/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (7)— Weymouth Effluent, Miramar Effluent, Pomona Groundwater +4 more
| |||
| Vanadium | 3.9 ug/LReported levelMiramar Groundwater Well #1 | 50 ug/LNL | Detected — no federal limit |
+By source (5)— Miramar Groundwater Well #1, Miramar Groundwater Well #2, Weymouth Effluent +2 more
| |||
Microbial
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Cryptosporidium | Not detectedRangeWeymouth Effluent | None set | None detected |
+By source (6)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +3 more
| |||
| Escherichia coli (E. coli)Escherichia coli — bacteria found in the gut of humans and animals. | 0 %RangePomona Groundwater | None set | None detected |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| Giardia lamblia | Not detectedRangeMiramar Effluent | None set | None detected |
+By source (6)— Miramar Effluent, Weymouth Effluent, Miramar Groundwater Well #1 +3 more
| |||
| Total ColiformA group of bacteria used as an indicator of overall water-system sanitation. | 0–1.37 %RangePomona Groundwater | None set | Detected — no federal limit |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
PFAS ("forever chemicals")
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Hexafluoropropylene oxide dimer acidHFPO-DA ('GenX chemicals'), a newer-generation PFAS replacement compound. | Not detected ng/LRangePomona Groundwater | 10 ng/LMCL | None detected |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| Perfluorononanoic acidPerfluorononanoic acid, a PFAS 'forever chemical.' | Not detected ng/LRangePomona Groundwater | 10 ng/LMCL | None detected |
+By source (8)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +5 more
| |||
| Nonafluoro-3,6-dioxaheptanoic acidNonafluoro-3,6-dioxaheptanoic acid, a PFAS-related compound. | 8 ng/LReported levelMiragrand Well | None set | Detected — no federal limit |
+By source (8)— Miragrand Well, Pomona Groundwater, Pomona Effluent +5 more
| |||
| Perfluoroheptanoic acidPerfluoroheptanoic acid, a PFAS 'forever chemical.' | 0–3.1 ng/LReported levelMiragrand Well | None set | Detected — no federal limit |
+By source (8)— Miragrand Well, Miramar Groundwater Well #1, Miramar Groundwater Well #2 +5 more
| |||
| PFBAPerfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' | 0–3.5 ng/LReported levelMiragrand Well | None set | Detected — no federal limit |
+By source (8)— Miragrand Well, Pomona Groundwater, Pomona Effluent +5 more
| |||
Source: Pomona, CA's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. utility is required to publish. The numbers on this page are the utility's own. A water-quality report covers an entire service area, not a single address.
People also ask about Pomona, CA's water
+Is Pomona, CA tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Pomona, CA water utility lists 3 contaminants at or above the federal limit: PFOS, PFOA, and Turbidity. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in Pomona, CA tap water?
68 contaminants were measured in Pomona, CA's 2024 Consumer Confidence Report, spanning metals, pfas ("forever chemicals"), and disinfection byproducts. 21 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in Pomona, CA tap water?
3 contaminants in Pomona, CA's 2024 report sit at or above the federal limit: PFOS (4.5× the limit); PFOA (1.8× the limit); Turbidity (1.3× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in Pomona, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is PFOS, at 4.5× the federal threshold. It belongs to the pfas ("forever chemicals") family of contaminants.
+Where does the data on this page come from?
Every value is transcribed from Pomona, CA's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is Pomona, CA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2024 report; a new report will replace it once the utility publishes its next annual update.
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