# City of Paso Robles Water Division — Paso Robles, Ca, CA — Drinking Water Quality (2023)

> Contaminant levels for the City of Paso Robles Water Division — Paso Robles, Ca, CA public water system from its 2023 Consumer Confidence Report, compared to federal limits.

- Page: https://www.thewatermap.com/water/ca/paso-robles-water-division-paso-robles-ca/2023
- JSON API: https://www.thewatermap.com/api/water/ca/paso-robles-water-division-paso-robles-ca/2023
- Source: the utility's annual Consumer Confidence Report (CCR)
- Verification: transcribed by a model, cross-checked by a second model, approved before publishing
- Reporting year: 2023
- Contaminants measured: 31
- Contaminants with a federal limit: 6
- Contaminants at or above the federal limit: 1
- Part of The Water Map — https://www.thewatermap.com

## Contaminants measured

| Contaminant | Category | Measured level | Sampling context | Federal limit | Status |
|---|---|---|---|---|---|
| Chlorine | Disinfectants | 0.3–2.2 mg/L (Range) | System-wide | No federal limit | Within the limit |
| HAA5 | Disinfection byproducts | 2.1–35.2 ug/L (Range) | System-wide | No federal limit | Within the limit |
| TTHM | Disinfection byproducts | 9.3–72.8 ug/L (Range) | System-wide | No federal limit | Approaching the limit |
| Fluoride | Inorganic chemicals | 0–0.3 mg/L (Range) | System-wide | 4 mg/L (MCL) | Within the limit |
| Nitrate | Inorganic chemicals | 0–7 mg/L (Range) | System-wide | 10 mg/L (MCL) | Within the limit |
| Arsenic | Metals | 0–6.1 ug/L (Range) | System-wide | No federal limit | Within the limit |
| Barium | Metals | 0–0.33 mg/L (Range) | System-wide | 2 mg/L (MCL) | Within the limit |
| Boron | Metals | 0–790 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Calcium | Metals | 26–110 mg/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Copper | Metals | 0.42 mg/L (90th percentile) | At the tap | 1.3 mg/L (Action level) | Within the limit |
| Lithium | Metals | 0–46.2 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Potassium | Metals | 1.1–2.8 mg/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Selenium | Metals | 0–20 ug/L (Range) | System-wide | No federal limit | Within the limit |
| Sodium | Metals | 12–140 mg/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Thallium | Metals | 0–1.8 ug/L (Range) | System-wide | No federal limit | Approaching the limit |
| Vanadium | Metals | 0–48 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Nitrate Nitrite | Other | 0–4.2 mg/L (Range) | System-wide | 10 mg/L (MCL) | Within the limit |
| Pce | Other | 0–0.17 ug/L (Range) | System-wide | No federal limit | Within the limit |
| Perfluorobutanesulfonic acid | PFAS ("forever chemicals") | 0–0.0081 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Perfluoroheptanoic acid | PFAS ("forever chemicals") | 0–0.0063 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Perfluorohexanesulfonic acid | PFAS ("forever chemicals") | 0–0.0052 ug/L (Range) | System-wide | No federal limit | Within the limit |
| Perfluorohexanoic acid | PFAS ("forever chemicals") | 0–0.02 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Perfluoropentanoic acid | PFAS ("forever chemicals") | 0–0.022 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| PFBA | PFAS ("forever chemicals") | 0–0.0061 ug/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| PFOA | PFAS ("forever chemicals") | 0–0.0063 ug/L (Range) | System-wide | No federal limit | At or above the limit |
| Alkalinity | Physical & aggregate | 120–323 mg/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Bicarbonate | Physical & aggregate | 140–396.7 mg/L (Range) | System-wide | No federal limit | Detected — no federal limit |
| Hardness | Physical & aggregate | 8.2–28.7 (Range) | System-wide | No federal limit | Detected — no federal limit |
| pH | Physical & aggregate | 7.2–8 (Range) | System-wide | No federal limit | Detected — no federal limit |
| Turbidity | Physical & aggregate | 100 (Reported level) | System-wide | No federal limit | Detected — no federal limit |
| Gross Alpha | Radionuclides | 0–7.2 pCi/L (Range) | System-wide | 15 pCi/L (MCL) | Within the limit |

## What these contaminants are

- **Chlorine** — A disinfectant added to drinking water to kill bacteria and viruses. Effective and necessary, but high residual levels can cause taste and odor issues; the EPA caps the residual disinfectant level.
- **HAA5** — Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. Long-term exposure above the federal limit is associated with an increased cancer risk.
- **TTHM** — Total trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. Long-term exposure above the federal limit is linked to liver, kidney, and central-nervous-system effects and increased cancer risk.
- **Fluoride** — A mineral often added to drinking water to help prevent tooth decay. Beneficial at low levels, but long-term exposure above the federal limit can cause bone disease and tooth mottling.
- **Nitrate** — A compound from fertilizer runoff, septic systems, and erosion of natural deposits. Levels above the federal limit can cause 'blue baby syndrome,' a serious oxygen-transport condition in infants.
- **Arsenic** — A naturally occurring element that also enters water from industry and agriculture. A known human carcinogen; long-term exposure is linked to skin, bladder, and lung cancer.
- **Barium** — A metal from erosion of natural deposits and industrial discharge. Long-term exposure above the federal limit can raise blood pressure.
- **Boron** — A naturally occurring element from rock and soil. No enforceable federal limit; the EPA has issued a health advisory level.
- **Calcium** — A naturally occurring mineral that contributes to water hardness. Not federally regulated for health; affects scaling and taste.
- **Copper** — A metal that enters water from corroding household plumbing. Short-term exposure causes stomach distress; long-term exposure can damage the liver and kidneys.
- **Lithium** — A naturally occurring element found in some groundwater. No enforceable federal limit; on the EPA contaminant candidate list for further study.
- **Potassium** — A naturally occurring mineral from rock and soil. Not federally regulated for health.
- **Selenium** — A trace element from natural deposits and industrial discharge. Essential in tiny amounts, but long-term exposure above the federal limit can cause hair and fingernail loss and circulatory problems.
- **Sodium** — A naturally occurring salt component. Not federally regulated for health; relevant for people on sodium-restricted diets.
- **Perfluorobutanesulfonic acid** — Perfluorobutanesulfonic acid, a shorter-chain PFAS 'forever chemical.' Has no standalone limit but is part of the EPA PFAS Hazard Index that limits PFAS in combination.
- **Perfluoroheptanoic acid** — Perfluoroheptanoic acid, a PFAS 'forever chemical.' Monitored under EPA rules; persistent in the environment.
- **Perfluorohexanesulfonic acid** — Perfluorohexanesulfonic acid, a PFAS 'forever chemical.' Regulated by the EPA at 10 parts per trillion and included in the PFAS Hazard Index.
- **Perfluorohexanoic acid** — Perfluorohexanoic acid, a shorter-chain PFAS 'forever chemical.' Monitored under EPA rules; persistent and widely detected.
- **Perfluoropentanoic acid** — Perfluoropentanoic acid, a shorter-chain PFAS 'forever chemical.' Monitored under EPA rules; persistent in the environment.
- **PFBA** — Perfluorobutanoic acid, a shorter-chain PFAS 'forever chemical.' Monitored under EPA rules; persistent in the environment and the human body.
- **PFOA** — Perfluorooctanoic acid, a PFAS 'forever chemical' once used in nonstick and stain-resistant products. Linked to cancer, liver damage, and immune effects; the EPA set an enforceable limit of 4 parts per trillion.
- **Alkalinity** — A measure of the water's capacity to neutralize acids. Not federally regulated for health; relevant to corrosion control and treatment.
- **Hardness** — A measure of dissolved calcium and magnesium minerals. Not federally regulated for health; affects scaling, soap use, and taste.
- **pH** — A measure of how acidic or basic the water is. Regulated only as a secondary standard; very low or high pH can corrode pipes or affect taste.
- **Turbidity** — A measure of cloudiness from suspended particles in the water. High turbidity can shelter microbes from disinfection; the EPA enforces it through a treatment-technique standard.
- **Gross Alpha** — Gross alpha particle activity — a combined measure of alpha-emitting radioactive substances. Long-term exposure above the federal limit increases cancer risk.

## How to read this

- A water-quality report covers an entire service area, not a single address.
- 'Federal limit' is the EPA standard (MCL, action level, treatment technique, etc.) that the measured level is compared against.
- 'At or above the federal limit' means the utility's own reported figure met or exceeded that standard.

_Figures are the utility's own published numbers. Generated 2026-06-04 from thewatermap.com._