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 — 27 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 68
- Over federal limit
- 27
- Approaching the limit
- 0
- Worst contaminant
- Magnesium
- Service area
- CA
2600.0× the limit
state-level CCR
At or above the federal limit
- MagnesiumMetals · Reported level25–26 mg/Llimit 0.01 mg/L · 2600.0× the limit
- Specific ConductancePhysical & aggregate · Range912–996limit 1 · 996.0× the limit
- CalciumMetals · Range49–76 mg/Llimit 0.1 mg/L · 760.0× the limit
- Total Dissolved SolidsPhysical & aggregate · Range573–632 mg/Llimit 1 mg/L · 632.0× the limit
- Combined RadiumRadionuclides · Reported level0–2024 pCi/Llimit 5 pCi/L · 404.8× the limit
- HardnessPhysical & aggregate · Reported level241–272 mg/Llimit 1 mg/L · 272.0× the limit
- AlkalinityPhysical & aggregate · Range140–170 mg/Llimit 1 mg/L · 170.0× the limit
- BoronMetals · Reported level140 ug/Llimit 1 ug/L · 140.0× the limit
- Gross AlphaRadionuclides · Reported level0–2024 pCi/Llimit 15 pCi/L · 134.9× the limit
- SodiumMetals · Reported level93–105 mg/Llimit 1 mg/L · 105.0× the limit
- UraniumRadionuclides · Reported level1.6–2024 pCi/Llimit 20 pCi/L · 101.2× the limit
- Gross Beta Particle ActivityRadionuclides · Reported level2024 pCi/Llimit 50 pCi/L · 40.5× the limit
- PotassiumMetals · Reported level4.6–5 mg/Llimit 0.2 mg/L · 25.0× the limit
- ChloroformDisinfection byproducts · Range0–11 ug/Llimit 1 ug/L · 11.0× the limit
- DibromochloromethaneDisinfection byproducts · Range0–10 ug/Llimit 1 ug/L · 10.0× the limit
- BromoformDisinfection byproducts · Range0–7.7 ug/Llimit 1 ug/L · 7.7× the limit
- BromodichloromethaneDisinfection byproducts · Range0–7.1 ug/Llimit 1 ug/L · 7.1× the limit
- LithiumMetals · Reported level32–40 ug/Llimit 10 ug/L · 4.0× the limit
- PFOSPFAS ("forever chemicals") · Range0–18 ng/Llimit 6.5 ng/L · 2.8× the limit
- Perfluoroheptanoic acidPFAS ("forever chemicals") · Range5 ng/Llimit 2 ng/L · 2.5× the limit
- Perfluorohexanoic acidPFAS ("forever chemicals") · Range0–5 ng/Llimit 2 ng/L · 2.5× the limit
- Perfluoropentanoic acidPFAS ("forever chemicals") · Reported level0–5.5 ng/Llimit 3 ng/L · 1.8× the limit
- PFOAPFAS ("forever chemicals") · Range0–7.1 ng/Llimit 5.1 ng/L · 1.4× the limit
- Perfluorononanoic acidPFAS ("forever chemicals") · Range5 ng/Llimit 4 ng/L · 1.3× the limit
- Chromium, HexavalentMetals · Reported level0–12 ug/Llimit 10 ug/L · 1.2× the limit
- Hexafluoropropylene oxide dimer acidPFAS ("forever chemicals") · Range5 ng/Llimit 5 ng/L · 1.0× the limit
- PFBAPFAS ("forever chemicals") · Range5 ng/Llimit 5 ng/L · 1.0× the limit
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
near national p90 (19.900000000000006 ng/L across detecting U.S. systems)
PFOA (Perfluorooctanoic acid)
● Over EPA limit (1.8×)Measured 7.1 ng/LEPA limit 4 ng/LSample year 2024Samples 1 detect / 15
near national p90 (13.649999999999999 ng/L across detecting U.S. systems)
PFHxS (Perfluorohexane sulfonic acid)
● Below limitMeasured 7.9 ng/LEPA limit 10 ng/LSample year 2024Samples 1 detect / 15
near national p90 (12.049999999999997 ng/L across detecting U.S. systems)
PFPeA
● Detected (no federal limit)Measured 4.4 ng/LSample year 2024Samples 1 detect / 15
below national p90 (15.95999999999999 ng/L across detecting U.S. systems)
PFBS
● Detected (no federal limit)Measured 3.2 ng/LSample year 2024Samples 1 detect / 15
below national p90 (13.909999999999979 ng/L across detecting U.S. systems)
Lithium
● Detected (no federal limit)Measured 9.3 mg/LSample year 2023Samples 1 detect / 15
below national p90 (76.59999999999991 mg/L across detecting U.S. systems)
PFHxA
● Detected (no federal limit)Measured 4.1 ng/LSample year 2024Samples 1 detect / 15
below national p90 (12.190000000000003 ng/L across detecting U.S. systems)
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.
Historical readings · EPA Six-Year Review (2012–2019)
7 contaminants historically over EPA limits in Pomona, CA
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
TCE worst: 2017 | 0.13 mg/L 26.0× | 0.005 mg/L | '12'13'14'15'16'17'18'19 |
DICHLOROETHYLENE 11 worst: 2012 | 0.061 mg/L 8.7× 7.4× the national p90 | 0.007 mg/L | '12'13'14'15'16'17'18'19 |
PCE worst: 2014 | 0.034 mg/L 6.8× | 0.005 mg/L | '12'13'14'15'16'17'18'19 |
NITRATE worst: 2016 | 29 mg/L 2.9× | 10 mg/L | '12'13'14'15'16'17'18'19 |
NITRATE NITRITE worst: 2018 | 22 mg/L 2.2× | 10 mg/L | '16'17'18'19 |
CHROMIUM worst: 2017 | 0.18 mg/L 1.8× 18.0× the national p90 | 0.1 mg/L | '12'13'14'15'16'17'18'19 |
ARSENIC worst: 2015 | 0.011 mg/L 1.1× near national p90 | 0.01 mg/L | '12'13'14'15'16'17'18 |
TTHM worst: 2012 | 0.051 mg/L within | 0.08 mg/L | '12'13'14'15'16'17'18'19 |
THALLIUM worst: 2015 | 0.0012 mg/L within | 0.002 mg/L | '15 |
DBCP worst: 2018 | 0.00011 mg/L within below national p90 | 0.0002 mg/L | '12'15'18 |
HAA5 worst: 2017 | 0.027 mg/L within | 0.06 mg/L | '12'13'14'15'16'17'18'19 |
FLUORIDE worst: 2013 | 0.6 mg/L within | 4 mg/L | '12'13'14'15'16'17'18'19 |
SELENIUM worst: 2018 | 0.0072 mg/L within | 0.05 mg/L | '14'15'18 |
BARIUM worst: 2012 | 0.1 mg/L within below national p90 | 2 mg/L | '12'13'16'18 |
URANIUM worst: 2018 | 0.007 ug/L within below national p90 | 30 ug/L | '12'13'14'15'16'18'19 |
DBAA worst: 2012 | 0.0034 mg/L | — | '12'13'14'15'16'17'18'19 |
DCAA worst: 2012 | 0.0072 mg/L | — | '12'13'14'15'16'17'18'19 |
MBAA worst: 2016 | 0.0024 mg/L | — | '16'17'18 |
TCAA worst: 2012 | 0.0058 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMODICHLOROMETHANE worst: 2012 | 0.013 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMOFORM worst: 2012 | 0.017 mg/L | — | '12'13'14'15'16'17'18'19 |
CHLOROFORM worst: 2012 | 0.015 mg/L | — | '12'13'14'15'16'17'18'19 |
DIBROMOCHLOROMETHANE worst: 2012 | 0.019 mg/L | — | '12'13'14'15'16'17'18'19 |
PWSID CA1910126 · Source: EPA Six-Year Review 4 (2012–2019). Values are the highest detection in each calendar year; non-detect years are omitted. Year tags above show every year with a detection.
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| MagnesiumA naturally occurring mineral that contributes to water hardness. | 25–26 mg/LReported levelWeymouth Effluent | 0.01 mg/LMCL | At or above the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Effluent +4 more
| |||
| CalciumA naturally occurring mineral that contributes to water hardness. | 49–76 mg/LRangePomona Groundwater | 0.1 mg/LMCL | At or above the limit |
+By source (7)— Pomona Groundwater, Weymouth Effluent, Miramar Groundwater Grand Well +4 more
| |||
| BoronA naturally occurring element from rock and soil. | 140 ug/LReported levelMiramar Effluent | 1 ug/LNL | At or above the limit |
+By source (5)— Miramar Effluent, Weymouth Effluent, Miramar Groundwater Well #2 +2 more
| |||
| SodiumA naturally occurring salt component. | 93–105 mg/LReported levelWeymouth Effluent | 1 mg/LMCL | At or above the limit |
+By source (7)— Weymouth Effluent, Miramar Effluent, Pomona Groundwater +4 more
| |||
| PotassiumA naturally occurring mineral from rock and soil. | 4.6–5 mg/LReported levelWeymouth Effluent | 0.2 mg/LMCL | At or above the limit |
+By source (7)— Weymouth Effluent, Miramar Effluent, Pomona Groundwater +4 more
| |||
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0–12 ug/LReported levelPomona Groundwater | 10 ug/LMCL | At or above the limit |
+By source (8)— Pomona Groundwater, Miramar Groundwater Miragrand Well, Miramar Groundwater Well #1 +5 more
| |||
| Chromium, TotalTotal chromium — the sum of all chromium forms, from natural deposits and industrial discharge. | 0–15 ug/LReported levelPomona Groundwater | 50 ug/LMCL | Within the limit |
+By source (7)— Pomona Groundwater, Weymouth Effluent, Miramar Groundwater Well #2 +4 more
| |||
| AluminumA common element sometimes used as a treatment coagulant. | 110–158 ug/LReported levelPomona Effluent | 1000 ug/LMCL | Within the limit |
+By source (14)— Pomona Effluent, Weymouth Effluent, Pomona Groundwater +11 more
| |||
| 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 (14)— Consumers' Taps, Pomona Groundwater, Pomona Groundwater +11 more
| |||
| Vanadium | 3.9 ug/LReported levelMiramar Groundwater Well #1 | 50 ug/LNL | Within the limit |
+By source (5)— Miramar Groundwater Well #1, Miramar Groundwater Well #2, Weymouth Effluent +2 more
| |||
| IronA naturally occurring metal common in groundwater. | Not detected ug/LRangeWeymouth Effluent | 300 ug/LMCL | None detected |
+By source (7)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #1 +4 more
| |||
| LeadA toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. | 0 ug/L90th percentileConsumers' Taps | 15 ug/LAction level | None detected |
+By source (8)— Consumers' Taps, Weymouth Effluent, Miramar Groundwater Grand Well +5 more
| |||
| ManganeseA naturally occurring metal from soil and rock. | Not detected ug/LRangeMiramar Effluent | 50 ug/LMCL | None detected |
+By source (7)— Miramar Effluent, Pomona Effluent, Miramar Groundwater Well #2 +4 more
| |||
| Strontium | Not detected pCi/LReported levelWeymouth Effluent | 8 pCi/LMCL | 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 levelMiramar Groundwater Grand Well | 5 mg/LMCL | None detected |
+By source (7)— Miramar Groundwater Grand Well, Miramar Groundwater Well #2, Pomona Effluent +4 more
| |||
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Specific ConductanceA measure of how well water conducts electricity, which tracks dissolved mineral content. | 912–996RangeWeymouth Effluent | 1MCL | At or above the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Groundwater Grand Well +4 more
| |||
| Total Dissolved SolidsTotal dissolved solids — the combined content of all dissolved minerals and salts. | 573–632 mg/LRangeWeymouth Effluent | 1 mg/LMCL | At or above the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Groundwater Grand Well +4 more
| |||
| HardnessA measure of dissolved calcium and magnesium minerals. | 241–272 mg/LReported levelWeymouth Effluent | 1 mg/LMCL | At or above the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Groundwater Well #2 +4 more
| |||
| AlkalinityA measure of the water's capacity to neutralize acids. | 140–170 mg/LRangePomona Effluent | 1 mg/LMCL | At or above the limit |
+By source (7)— Pomona Effluent, Miramar Groundwater Well #2, Miramar Groundwater Grand Well +4 more
| |||
| OdorA measure of detectable smell in the water. | 1Reported levelMiramar Groundwater Well #1 | 3MCL | Within the limit |
+By source (7)— Miramar Groundwater Well #1, Miramar Groundwater Grand Well, Miramar Groundwater Well #2 +4 more
| |||
| TurbidityA measure of cloudiness from suspended particles in the water. | 0–1.3 NTUReported levelMiramar Groundwater Well #1 | 5 NTUMCL | Within the limit |
+By source (15)— Miramar Groundwater Well #1, Pomona Effluent, Pomona Groundwater +12 more
| |||
| ColorA measure of visible tint in the water. | 1RangeWeymouth Effluent | 15MCL | Within the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Groundwater Well #1 +4 more
| |||
| pHA measure of how acidic or basic the water is. | 6.64–7.73Reported levelMiragrand Well | None set | Detected — no federal limit |
+By source (8)— Miragrand Well, Pomona Groundwater, Miramar Groundwater Well #1 +5 more
| |||
| TOCTotal organic carbon — a measure of organic material dissolved in the water. | 2.4 mg/LReported levelWeymouth Effluent | None set | Detected — no federal limit |
+By source (3)— Weymouth Effluent, Pomona Effluent, Miramar Effluent
| |||
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Combined RadiumCombined radium-226 and radium-228 — naturally occurring radioactive elements. | 0–2024 pCi/LReported levelPomona Groundwater | 5 pCi/LMCL | At or above the limit |
+By source (5)— Pomona Effluent, Pomona Groundwater, Miramar Groundwater Miragrand Well +2 more
| |||
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | 0–2024 pCi/LReported levelPomona Effluent | 15 pCi/LMCL | At or above the limit |
+By source (6)— Pomona Effluent, Pomona Groundwater, Miramar Effluent +3 more
| |||
| Gross Beta Particle ActivityGross beta particle activity — a combined measure of beta-emitting radioactive substances. | 2024 pCi/LReported levelPomona Groundwater | 50 pCi/LMCL | At or above the limit |
+By source (4)— Pomona Groundwater, Pomona Effluent, Weymouth Effluent +1 more
| |||
PFAS ("forever chemicals")
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Perfluoroheptanoic acidPerfluoroheptanoic acid, a PFAS 'forever chemical.' | 5 ng/LRangePomona Groundwater | 2 ng/LMCL | At or above the limit |
+By source (7)— Pomona Groundwater, Miragrand Well, Miramar Effluent +4 more
| |||
| Perfluorononanoic acidPerfluorononanoic acid, a PFAS 'forever chemical.' | 5 ng/LRangePomona Groundwater | 4 ng/LMCL | At or above the limit |
+By source (7)— Pomona Groundwater, Miramar Groundwater Well #1, Miramar Groundwater Well #2 +4 more
| |||
| Hexafluoropropylene oxide dimer acidHFPO-DA ('GenX chemicals'), a newer-generation PFAS replacement compound. | 5 ng/LRangePomona Groundwater | 5 ng/LMCL | At or above the limit |
+By source (7)— Pomona Groundwater, Miramar Groundwater Well #1, Miramar Effluent +4 more
| |||
| PFBAPerfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' | 5 ng/LRangePomona Groundwater | 5 ng/LMCL | At or above the limit |
+By source (7)— Pomona Groundwater, Miragrand Well, Miramar Groundwater Well #1 +4 more
| |||
| Nonafluoro-3,6-dioxaheptanoic acidNonafluoro-3,6-dioxaheptanoic acid, a PFAS-related compound. | 8 ng/LReported levelMiragrand Well | 20 ng/LMCL | Within the limit |
+By source (7)— Miragrand Well, Pomona Groundwater, Miramar Effluent +4 more
| |||
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| PerchlorateA chemical used in rocket fuel and fireworks that can also form during disinfection. | 0–3.5 ug/LReported levelPomona Groundwater | 6 ug/LMCL | Within the limit |
+By source (7)— Pomona Groundwater, Miramar Groundwater Grand Well, Miramar Groundwater Well #1 +4 more
| |||
| BromateA disinfection byproduct formed when bromide-containing water is treated with ozone. | 2 ug/LReported levelWeymouth Effluent | 10 ug/LMCL | Within the limit |
| ChlorateA byproduct that can form during disinfection, especially when hypochlorite solutions degrade. | 80 ug/LReported levelWeymouth Effluent | 800 ug/LNL | Within the limit |
+By source (5)— Weymouth Effluent, Miramar Effluent, Miramar Groundwater Well #2 +2 more
| |||
| NDMA | Not detected ng/LReported levelMiramar Effluent | 10 ng/LNL | None detected |
+By source (3)— Miramar Effluent, Pomona Groundwater, Weymouth Effluent
| |||
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TrichloroethyleneAn industrial solvent (TCE) used in metal degreasing. | 0–2.7 ug/LReported levelPomona Groundwater | 5 ug/LMCL | Within the limit |
+By source (8)— Pomona Groundwater, Miramar Groundwater Miragrand Well, Miramar Effluent +5 more
| |||
| TetrachloroethyleneAn industrial solvent (PCE) used in dry cleaning and degreasing. | 0–2 ug/LReported levelPomona Groundwater | 5 ug/LMCL | Within the limit |
+By source (8)— Pomona Groundwater, Miramar Groundwater Well #1, Miramar Groundwater Well #2 +5 more
| |||
| 1,2,3-TCP | Not detected ng/LReported levelMiramar Groundwater Well #1 | 5 ng/LMCL | None detected |
+By source (8)— Miramar Groundwater Well #1, Miramar Groundwater Miragrand Well, Pomona Effluent +5 more
| |||
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| SulfateA naturally occurring mineral from rock and soil. | 200–225 mg/LRangeWeymouth Effluent | 500 mg/LMCL | Within the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Effluent +4 more
| |||
| ChlorideA naturally occurring salt compound. | 96–106 mg/LRangeWeymouth Effluent | 500 mg/LMCL | Within the limit |
+By source (7)— Weymouth Effluent, Pomona Groundwater, Miramar Effluent +4 more
| |||
| Asbestos | Not detected MFLReported levelMiramar Groundwater Well #2 | 7 MFLMCL | None detected |
+By source (8)— Miramar Groundwater Well #2, Weymouth Effluent, Miramar Groundwater Miragrand Well +5 more
| |||
| Cyanide | Not detected ug/LReported levelMiramar Effluent | 150 ug/LMCL | None detected |
+By source (7)— Miramar Effluent, Weymouth Effluent, Pomona Effluent +4 more
| |||
| NitriteA compound from fertilizer runoff, sewage, and erosion of natural deposits. | Not detected mg/LReported levelMiramar Groundwater Well #1 | 1 mg/LMCL | None detected |
+By source (6)— Miramar Groundwater Well #1, Miramar Groundwater Grand Well, Weymouth Effluent +3 more
| |||
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChlorineA disinfectant added to drinking water to kill bacteria and viruses. | 0.03–1.42 mg/LReported levelMiramar Groundwater Well #1 | 4 mg/LMRDL | Within the limit |
+By source (8)— Miramar Groundwater Well #1, Miramar Groundwater Miragrand Well, Pomona Groundwater +5 more
| |||
Microbial
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Cryptosporidium | Not detectedReported levelMiramar Groundwater Miragrand Well | None set | None detected |
+By source (6)— Miramar Groundwater Miragrand Well, Weymouth Effluent, Miramar Groundwater Grand Well +3 more
| |||
| Escherichia coli (E. coli)Escherichia coli — bacteria found in the gut of humans and animals. | 0Reported levelWeymouth Effluent | None set | None detected |
+By source (8)— Weymouth Effluent, Miramar Groundwater Well #2, Miramar Effluent +5 more
| |||
| Giardia lamblia | Not detectedReported levelMiramar Groundwater Grand Well | None set | None detected |
+By source (6)— Miramar Groundwater Grand Well, Miramar Effluent, Miramar Groundwater Miragrand Well +3 more
| |||
| Total ColiformA group of bacteria used as an indicator of overall water-system sanitation. | 0–1.37 %Reported levelMiramar Groundwater Grand Well | None set | Detected — no federal limit |
+By source (8)— Miramar Groundwater Grand Well, Pomona Groundwater, Miramar Groundwater Miragrand Well +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 27 contaminants at or above the federal limit: Magnesium, Specific Conductance, Calcium, Total Dissolved Solids, Combined Radium, Hardness, Alkalinity, Boron, Gross Alpha, Sodium, Uranium, Gross Beta Particle Activity, Potassium, Chloroform, Dibromochloromethane, Bromoform, Bromodichloromethane, Lithium, PFOS, Perfluoroheptanoic acid, Perfluorohexanoic acid, Perfluoropentanoic acid, PFOA, Perfluorononanoic acid, Chromium, Hexavalent, Hexafluoropropylene oxide dimer acid, and PFBA. 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. 62 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?
27 contaminants in Pomona, CA's 2024 report sit at or above the federal limit: Magnesium (2600.0× the limit); Specific Conductance (996.0× the limit); Calcium (760.0× the limit); Total Dissolved Solids (632.0× the limit); Combined Radium (404.8× the limit); Hardness (272.0× the limit); Alkalinity (170.0× the limit); Boron (140.0× the limit); Gross Alpha (134.9× the limit); Sodium (105.0× the limit); Uranium (101.2× the limit); Gross Beta Particle Activity (40.5× the limit); Potassium (25.0× the limit); Chloroform (11.0× the limit); Dibromochloromethane (10.0× the limit); Bromoform (7.7× the limit); Bromodichloromethane (7.1× the limit); Lithium (4.0× the limit); PFOS (2.8× the limit); Perfluoroheptanoic acid (2.5× the limit); Perfluorohexanoic acid (2.5× the limit); Perfluoropentanoic acid (1.8× the limit); PFOA (1.4× the limit); Perfluorononanoic acid (1.3× the limit); Chromium, Hexavalent (1.2× the limit); Hexafluoropropylene oxide dimer acid (1.0× the limit); PFBA (1.0× 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 Magnesium, at 2600.0× the federal threshold. It belongs to the metals 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.