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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
EPA records for CAL-WATER SERVICE CO.-CHICO • Updated October 2026
Grade C — based on EPA compliance records, lead testing and PFAS monitoring
CAL-WATER SERVICE CO.-CHICO has a mixed record — read the reasons below; the deductions come from real EPA violations, lead results or PFAS detections, not from a template.
Chico, CA tap water is legal to drink but grades C on EPA's records, mainly because of PFOA or PFOS measured at or above the 4 ppt federal limit in 2023–2025 EPA sampling. A certified filter matched to that finding is a reasonable precaution.
Chico, CA tap water is legal to drink but grades C on EPA's records, mainly because of PFOA or PFOS measured at or above the 4 ppt federal limit in 2023–2025 EPA sampling. A certified filter matched to that finding is a reasonable precaution.
CAL-WATER SERVICE CO.-CHICO's most recent Lead and Copper Rule result (2021-01-01 to 2023-12-31) was 0 ppb at the 90th percentile, below EPA's 15 ppb action level. Because lead usually comes from service lines and household plumbing, homes built before 1986 should still test at the tap.
Yes. EPA's UCMR5 sampling (2023-09-18 to 2024-07-23) detected PFBS, PFHxA, PFHxS, PFOA, PFOS, PFPeA, with PFOA or PFOS at or above the 4 ppt federal MCL. Reverse osmosis and certified activated-carbon filters reduce PFAS.
No. EPA's SDWIS shows no violations of any kind for CAL-WATER SERVICE CO.-CHICO since 2016.
CAL-WATER SERVICE CO.-CHICO reports groundwater as its primary source and serves about 114,925 people (EPA PWSID CA0410002).
We recommend one. Reverse osmosis or a PFAS-certified carbon filter addresses the PFAS result.
Compare filter options for your Chico tap water
PFOA or PFOS was measured at or above EPA's 4 ppt limit in Chico's UCMR5 sampling.
See the filters matched to Chico's EPA results → — which certification actually removes what was found here, and what it does not touch.
Unsure which contaminants to treat? Compare home kits and certified lab testing before buying.
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CAL-WATER SERVICE CO.-CHICO · SDWIS records since 2016 · 5-year window starts 2021-09-13
EPA records no health-based violations for this system in the last five years.
No violations of any kind on file since 2016.
Source: ECHO SDWA bulk download (SDWA_VIOLATIONS_ENFORCEMENT.csv, SDWIS 2026Q2, file dated 2026-07-09, fetched 2026-09-13)
EPA Lead and Copper Rule 90th-percentile results reported by CAL-WATER SERVICE CO.-CHICO
Well below the 15 ppb action level. In the most recent monitoring period on file (2021-01-01 to 2023-12-31), 90% of the homes CAL-WATER SERVICE CO.-CHICO sampled had lead at or below 0 ppb.
EPA's action level is 15 ppb (dropping to 10 ppb under the 2024 Lead and Copper Rule Improvements). There is no safe level of lead; the 90th-percentile figure describes the system, not your tap — homes with lead service lines or pre-1986 plumbing can be higher.
| Monitoring period | Lead 90th percentile | vs 15 ppb action level |
|---|---|---|
| 2021-01-01 → 2023-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2018-01-01 → 2020-12-31 | 1.26 ppb | Well below the 15 ppb action level |
| 2015-01-01 → 2017-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2012-01-01 → 2014-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2011-01-01 → 2013-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2008-01-01 → 2010-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2005-01-01 → 2007-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2004-01-01 → 2004-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2002-01-01 → 2004-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2001-01-01 → 2003-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2001-01-01 → 2001-12-31 | 0 ppb | Well below the 15 ppb action level |
| 1999-01-01 → 2001-12-31 | 0 ppb | Well below the 15 ppb action level |
Source: ECHO SDWA bulk download (SDWA_LCR_SAMPLES.csv, SDWIS 2026Q2, file dated 2026-07-09, fetched 2026-09-13)
EPA UCMR5 monitoring, 2023-09-18 to 2024-07-23 · 2,146 PFAS results at entry points to the distribution system
PFOA and PFOS and PFHxS measured at or above EPA's legal limit in at least one sample. Utilities have until 2029 (2031 under EPA's proposed extension) to comply with the 2024 PFAS rule, so a result above the MCL today is not yet a violation — but it is the number that matters for your health.
| Compound | Detects / samples | Max (ppt) | Reporting limit | EPA MCL |
|---|---|---|---|---|
| PFOA | 2 / 74 | 6.8 | 4 ppt | 4 ppt |
| PFOS | 15 / 74 | 22.5 | 4 ppt | 4 ppt |
| PFHxS | 19 / 74 | 22.1 | 3 ppt | 10 ppt |
| PFNA | 0 / 74 | < 4 | 4 ppt | 10 ppt |
| HFPO-DA | 0 / 74 | < 5 | 5 ppt | 10 ppt |
| PFBS | 6 / 74 | 9.6 | 3 ppt | hazard index only |
| PFHxA | 2 / 74 | 6 | 3 ppt | hazard index only |
| PFPeA | 2 / 74 | 5.3 | 3 ppt | hazard index only |
“< 4 ppt” means below the laboratory reporting limit, not zero. ppt = parts per trillion (ng/L). Results are for finished water leaving the treatment plant.
Lithium (also monitored under UCMR5, not a PFAS): detected in 3 of 74 samples, max 11.7 µg/L. There is no federal limit for lithium.
What PFAS are and how to remove them → · Best filters for PFAS →
Source: UCMR5 occurrence data, EPA Data Summary July 2026 (UCMR5_All.txt)
EPA Six-Year Review 4 compliance samples for CAL-WATER SERVICE CO.-CHICO · finished water only · dated data, released 2024
These are the regulated-contaminant samples CAL-WATER SERVICE CO.-CHICO reported to its state between 2012 and 2019 — the most recent nationwide sample-level dataset EPA has published. Every scored contaminant stayed within its Maximum Contaminant Level (MCL) and averaged below 80% of the limit. Treat this as history, not today's tap water.
| Contaminant | Samples | Average | Max | EPA limit | Status |
|---|---|---|---|---|---|
| Nitrate (as N) | 123119 detects | 2.584 mg/L | 5.4 mg/L | 10 mg/LMCL | Within MCL |
| Total trihalomethanes (TTHM) | 59373 detects | 0.2 µg/L | 11.8 µg/L | 80 µg/LMCL (LRAA) | Within MCL |
| Haloacetic acids (HAA5) | 1080 detects | 0 µg/L | ND | 60 µg/LMCL (LRAA) | Within MCL |
Averages count non-detects as zero. TTHM and HAA5 limits are locational running annual averages, so a single high sample is not a violation — we grade those on the average only. Lead and copper rows are individual tap samples and are shown for context; compliance (and our score) uses the 90th-percentile result above. LRAA = locational running annual average; ND = not detected.
Source: SYR4 Six-Year Review compliance monitoring data 2012–2019 (released 2024-03)
A point-of-use (under-sink) system typically runs $200-$600 installed; whole-house treatment $1,000-$3,000+ depending on flow and what has to come out. Tell us where you are and a certified water-treatment installer serving Chico will follow up - no obligation.
CAL-WATER SERVICE CO.-CHICO · 31,115 service lines inventoried · Q2 2026 snapshot
CAL-WATER SERVICE CO.-CHICO reports no confirmed lead service lines, but 19,384 lines (62%) have not yet been verified, so lead cannot be ruled out for those homes. Utilities must keep investigating unknown lines under EPA's Lead and Copper Rule Improvements.
Source: EPA SDWIS Service Line Inventory (Q2 2026) · PWS ID CA0410002 · See all California lead service lines. We may earn a commission from filters and test kits, at no extra cost to you.
Groundwater systems draw from wells; naturally occurring arsenic, nitrate, radium and uranium are the readings to watch, along with PFAS near industrial or military sites.
How to test your tap water and the treatment options that actually fit Chico homes
The most reliable way to know what is actually coming out of your tap is a certified mail-in lab test. City-wide EPA data (like the report above) reflects the water leaving the treatment plant, but contaminants such as lead and copper can be picked up from your own service line and household plumbing — so the water at your Chico faucet can differ from the system average. A state-certified lab measures dozens of contaminants at once with results you can trust; you can also find one near you through the EPA's certified-lab list at epa.gov/dwlabcert. Hardware-store test strips are cheaper and instant, but they only screen for a few basics (chlorine, hardness, pH, and a rough lead pass/fail) and are far less accurate — treat them as a first look, not a diagnosis.
Match the treatment to what your test finds. Reverse osmosis (RO) removes the widest range of contaminants — lead, arsenic, nitrate, PFAS, and dissolved solids — which makes an under-sink reverse osmosis system the most thorough choice for Chico households with heavy-metal or PFAS concerns. If your main issue is taste, odor, or chlorine, an activated carbon filter (pitcher, faucet, or under-sink) is simpler and cheaper and handles chlorine and many organic compounds well, though carbon alone does not remove arsenic, nitrate, or most PFAS. NSF-certified pitchers rated for lead reduction are the easiest way to start today while you decide on a permanent setup.
We may earn a commission from testing kits and filters purchased through these links, at no extra cost to you.
What Chico residents measured at their own tap (ZIPs 95926, 95929). All reader results →
Reader submissions are unverified and shown separately from EPA data. They reflect one tap on one day, not the utility's compliance record.
No reader results for Chico yet - yours would be the first. A hardness or TDS number from a $10 strip kit is enough to start the map.
Help build the first reader-sourced water map. Enter whatever your test strip, TDS pen or lab report shows - one number is enough.
Chico ranks #122 of 163 graded California cities.
Deep-dive guides for the specific contaminants EPA data flagged in Chico's water, with removal options for each.
Chico, CA tap water is legal to drink but grades C on EPA's records, mainly because of PFOA or PFOS measured at or above the 4 ppt federal limit in 2023–2025 EPA sampling. A certified filter matched to that finding is a reasonable precaution.
CAL-WATER SERVICE CO.-CHICO's most recent Lead and Copper Rule result (2021-01-01 to 2023-12-31) was 0 ppb at the 90th percentile, below EPA's 15 ppb action level. Because lead usually comes from service lines and household plumbing, homes built before 1986 should still test at the tap.
Yes. EPA's UCMR5 sampling (2023-09-18 to 2024-07-23) detected PFBS, PFHxA, PFHxS, PFOA, PFOS, PFPeA, with PFOA or PFOS at or above the 4 ppt federal MCL. Reverse osmosis and certified activated-carbon filters reduce PFAS.
No. EPA's SDWIS shows no violations of any kind for CAL-WATER SERVICE CO.-CHICO since 2016.
CAL-WATER SERVICE CO.-CHICO reports groundwater as its primary source and serves about 114,925 people (EPA PWSID CA0410002).
We recommend one. Reverse osmosis or a PFAS-certified carbon filter addresses the PFAS result.
PFOA or PFOS was measured at or above EPA's 4 ppt limit in Chico's UCMR5 sampling.
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Reverse osmosis systems for PFAS
Reverse osmosis is the most thorough filtration class against PFAS — browse Waterdrop RO systems and check each model’s own tested claims.
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Whole-house system — treats every tap at the source
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Based on contaminants detected in your water, these resources may be helpful:
Find the right filter for your Chico water quality needs:
Tap water is one piece of the picture — our sister sites cover the rest for Chico, CA.
Predicted indoor radon by ZIP vs. the EPA 4 pCi/L action level.
Arsenic and nitrate risk for homes on a well instead of city water.
Understand your water better with our in-depth guides on contaminants, filtration, and water safety.