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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 NOGALES CITY OF • Updated September 2026
Grade D — based on EPA compliance records, lead testing and PFAS monitoring
NOGALES CITY OF has notable problems in EPA's records — health-based violations, elevated lead or PFAS above the federal limit. A certified filter is a reasonable precaution.
Nogales, AZ tap water is legal to drink but grades D on EPA's records, mainly because of 2 health-based EPA violations in the last five years and arsenic averaging 5.8 ug/l against a 10 ug/l limit in 2012–2019 samples (2 over the limit). A certified filter matched to those findings is a reasonable precaution.
Nogales, AZ tap water is legal to drink but grades D on EPA's records, mainly because of 2 health-based EPA violations in the last five years and arsenic averaging 5.8 ug/l against a 10 ug/l limit in 2012–2019 samples (2 over the limit). A certified filter matched to those findings is a reasonable precaution.
NOGALES CITY OF's most recent Lead and Copper Rule result (2022-01-01 to 2024-12-31) 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.
No. None of the 290 UCMR5 PFAS results for NOGALES CITY OF (2023-09-27 to 2025-12-29) were at or above the reporting limit of roughly 3–5 ppt.
NOGALES CITY OF has 212 violations on file since 2016: 2 health-based in the last five years and 17 monitoring or reporting violations in that window. Monitoring violations are paperwork lapses, not measured contamination.
NOGALES CITY OF reports groundwater as its primary source and serves about 22,000 people (EPA PWSID AZ0412004).
We recommend one. Check which contaminant the violations involved (table above) and choose a filter certified for it.
Compare filter options for your Nogales tap water
NOGALES CITY OF has 2 health-based EPA violations in the last five years.
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NOGALES CITY OF · SDWIS records since 2016 · 5-year window starts 2021-09-13
EPA records 2 health-based violations for this system in the last five years, all of which are marked resolved or archived. Health-based violations mean a contaminant exceeded its Maximum Contaminant Level (MCL) or a required treatment step was not met.
| Violation | Category | Compliance period | Status |
|---|---|---|---|
| LSL InventoryLEAD AND COPPER RULE REVISIONS | Treatment technique | 2024-10-17 | Resolvedreturned 2026-02-20 |
| Failure To Address DeficiencyGroundwater Rule | Treatment technique | 2021-11-15 | Resolvedreturned 2022-03-02 |
| Monitoring, RegularArsenic | Monitoring & reporting | 2025-10-01 → 2025-12-31 | Archived |
| Monitoring, RegularArsenic | Monitoring & reporting | 2025-07-01 → 2025-09-30 | Archived |
| Monitoring, RegularNitrate | Monitoring & reporting | 2025-07-01 → 2025-09-30 | Resolvedreturned 2025-09-30 |
| Monitoring and Reporting (DBP)Chlorine | Monitoring & reporting | 2025-07-01 → 2025-07-31 | Resolvedreturned 2025-07-31 |
| Public Notification Violation for NPDWR ViolationPublic Notice | Other | 2024-12-20 | Resolvedreturned 2025-02-06 |
| LSL ReportingLEAD AND COPPER RULE REVISIONS | Reporting | 2024-10-17 | Resolvedreturned 2026-02-20 |
| Monitoring and Reporting (DBP)TTHM | Monitoring & reporting | 2024-10-01 → 2024-12-31 | Resolvedreturned 2024-12-31 |
| Monitoring and Reporting (DBP)Total Haloacetic Acids (HAA5) | Monitoring & reporting | 2024-10-01 → 2024-12-31 | Resolvedreturned 2024-12-31 |
| Monitoring, RegularArsenic | Monitoring & reporting | 2024-10-01 → 2024-12-31 | Resolvedreturned 2024-12-31 |
| Public Notification Violation for NPDWR ViolationPublic Notice | Other | 2024-04-28 | Resolvedreturned 2024-06-19 |
| Monitoring and Reporting (DBP)Total Haloacetic Acids (HAA5) | Monitoring & reporting | 2023-10-01 → 2023-12-31 | Resolvedreturned 2023-12-31 |
| Monitoring, RegularArsenic | Monitoring & reporting | 2023-10-01 → 2023-12-31 | Resolvedreturned 2023-12-31 |
| Monitoring and Reporting (DBP)TTHM | Monitoring & reporting | 2023-10-01 → 2023-12-31 | Resolvedreturned 2023-12-31 |
| Report Sample Result/Fail Monitor (RTCR)Revised Total Coliform Rule | Reporting | 2023-07-01 | Resolvedreturned 2023-08-18 |
| Monitoring, RegularArsenic | Monitoring & reporting | 2023-07-01 → 2023-09-30 | Resolvedreturned 2023-09-30 |
| Monitoring and Reporting (DBP)Chlorine | Monitoring & reporting | 2023-04-01 → 2023-06-30 | Resolvedreturned 2023-06-30 |
| Monitoring, RegularArsenic | Monitoring & reporting | 2023-01-01 → 2023-03-31 | Resolvedreturned 2023-03-31 |
| Monitoring, RegularNitrate | Monitoring & reporting | 2023-01-01 → 2023-12-31 | Resolvedreturned 2023-12-31 |
| Monitoring, RegularNitrate | Monitoring & reporting | 2023-01-01 → 2023-12-31 | Resolvedreturned 2023-12-31 |
| Public Notification Violation for NPDWR ViolationPublic Notice | Other | 2020-02-13 | Resolvedreturned 2021-02-23 |
| Report Sample Result/Fail Monitor (RTCR)Revised Total Coliform Rule | Reporting | 2020-01-01 | Resolvedreturned 2020-02-26 |
| Monitoring and Reporting (DBP)Total Haloacetic Acids (HAA5) | Monitoring & reporting | 2019-08-01 → 2019-10-31 | Resolvedreturned 2019-10-31 |
| Monitoring and Reporting (DBP)TTHM | Monitoring & reporting | 2019-08-01 → 2019-10-31 | Resolvedreturned 2019-10-31 |
Showing 25 of 212 violations on file. Full record on EPA ECHO.
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 NOGALES CITY OF
Well below the 15 ppb action level. In the most recent monitoring period on file (2022-01-01 to 2024-12-31), 90% of the homes NOGALES CITY OF 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 |
|---|---|---|
| 2022-01-01 → 2024-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2019-01-01 → 2021-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2016-01-01 → 2018-12-31 | 1 ppb | Well below the 15 ppb action level |
| 2013-01-01 → 2015-12-31 | 1.1 ppb | Well below the 15 ppb action level |
| 2010-01-01 → 2012-12-31 | 1.9 ppb | Well below the 15 ppb action level |
| 2009-01-01 → 2011-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2006-01-01 → 2008-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2004-01-01 → 2006-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2003-01-01 → 2005-12-31 | 0 ppb | Well below the 15 ppb action level |
| 2003-01-01 → 2003-12-31 | 5 ppb | Below the action level, but detectable |
| 1992-07-01 → 1992-12-31 | 27 ppb | Above 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, 2023-09-27 to 2025-12-29 · 290 PFAS results at entry points to the distribution system
No PFAS detected. None of the 290 UCMR5 PFAS results for NOGALES CITY OF were at or above the method reporting limit. Reporting limits are about 3–5 ppt, so “not detected” means below that threshold — not proven zero.
| Compound | Detects / samples | Max (ppt) | Reporting limit | EPA MCL |
|---|---|---|---|---|
| PFOA | 0 / 10 | < 4 | 4 ppt | 4 ppt |
| PFOS | 0 / 10 | < 4 | 4 ppt | 4 ppt |
| PFHxS | 0 / 10 | < 3 | 3 ppt | 10 ppt |
| PFNA | 0 / 10 | < 4 | 4 ppt | 10 ppt |
| HFPO-DA | 0 / 10 | < 5 | 5 ppt | 10 ppt |
| PFBS | 0 / 10 | < 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 9 of 10 samples, max 57.4 µg/L. There is no federal limit for lithium.
What PFAS are and how to remove them →
Source: UCMR5 occurrence data, EPA Data Summary July 2026 (UCMR5_All.txt)
EPA Six-Year Review 4 compliance samples for NOGALES CITY OF · finished water only · dated data, released 2024
These are the regulated-contaminant samples NOGALES CITY OF reported to its state between 2012 and 2019 — the most recent nationwide sample-level dataset EPA has published. Arsenic is flagged below; the status column explains why. Treat this as history, not today's tap water.
| Contaminant | Samples | Average | Max | EPA limit | Status |
|---|---|---|---|---|---|
| Arsenic | 8074 detects | 5.831 µg/L | 13 µg/L | 10 µg/LMCL | 2 of 80 samples over MCL |
| Nitrate (as N) | 3931 detects | 1.362 mg/L | 3.7 mg/L | 10 mg/LMCL | Within MCL |
| Fluoride | 135 detects | 0.601 mg/L | 3 mg/L | 4 mg/LMCL | Within MCL |
| Chromium (total) | 130 detects | 0 µg/L | ND | 100 µg/LMCL | Not detected |
| Uranium (combined) | 1514 detects | 4.347 µg/L | 7.9 µg/L | 30 µg/LMCL | Within MCL |
| Radium-226/228 | 140 detects | 0 pCi/L | ND | 5 pCi/LMCL | Not detected |
| Gross alpha | 1510 detects | 0.893 pCi/L | 4.9 pCi/L | 15 pCi/LMCL | Within MCL |
| Total trihalomethanes (TTHM) | 13897 detects | 4.899 µg/L | 51 µg/L | 80 µg/LMCL (LRAA) | Within MCL |
| Haloacetic acids (HAA5) | 13823 detects | 0.396 µg/L | 3.6 µg/L | 60 µg/LMCL (LRAA) | Within MCL |
| Lead (tap samples) | 9042 detects | 0.56 µg/L | 4.6 µg/L | 15 µg/Laction level (90th percentile) | Reported, not scored (compliance is on the 90th percentile) |
| Copper (tap samples) | 9088 detects | 102.378 µg/L | 1000 µg/L | 1300 µg/Laction level (90th percentile) | Reported, not scored (compliance is on the 90th percentile) |
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 Nogales will follow up - no obligation.
NOGALES CITY OF · 6,047 service lines inventoried · Q2 2026 snapshot
NOGALES CITY OF reports no lead or galvanized-requiring-replacement service lines and has classified 100% of its 6,047 lines as non-lead. Lead can still come from pre-1986 plumbing and fixtures inside a home.
Source: EPA SDWIS Service Line Inventory (Q2 2026) · PWS ID AZ0412004 · See all Arizona 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 Nogales 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 Nogales 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 Nogales 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 Nogales residents measured at their own tap (ZIPs 85621). 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 Nogales 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.
Nogales ranks #31 of 37 graded Arizona cities.
Deep-dive guides for the specific contaminants EPA data flagged in Nogales's water, with removal options for each.
Nogales, AZ tap water is legal to drink but grades D on EPA's records, mainly because of 2 health-based EPA violations in the last five years and arsenic averaging 5.8 ug/l against a 10 ug/l limit in 2012–2019 samples (2 over the limit). A certified filter matched to those findings is a reasonable precaution.
NOGALES CITY OF's most recent Lead and Copper Rule result (2022-01-01 to 2024-12-31) 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.
No. None of the 290 UCMR5 PFAS results for NOGALES CITY OF (2023-09-27 to 2025-12-29) were at or above the reporting limit of roughly 3–5 ppt.
NOGALES CITY OF has 212 violations on file since 2016: 2 health-based in the last five years and 17 monitoring or reporting violations in that window. Monitoring violations are paperwork lapses, not measured contamination.
NOGALES CITY OF reports groundwater as its primary source and serves about 22,000 people (EPA PWSID AZ0412004).
We recommend one. Check which contaminant the violations involved (table above) and choose a filter certified for it.
NOGALES CITY OF has 2 health-based EPA violations in the last five years.
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Based on contaminants detected in your water, these resources may be helpful:
Find the right filter for your Nogales water quality needs:
Tap water is one piece of the picture — our sister sites cover the rest for Nogales, AZ.
County radon prediction and EPA zone for homes around Nogales.
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.