City of Williams
What EPA’s and CDC’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.
- Serves
- 3,145 people
- Connections
- 1,883
- Water source
- Surface water
- Based in
- Williams, AZ
- County
- Coconino
- Owner
- Local government
The ZIP code it serves
The short answer
1 result is above EPA’s legal limit, and 1 more is above the health goal. The worst: Arsenic, above the legal limit. 8 health-based violations since 2016.
What handles itWhat was found
Lead and copper: EPA SDWIS monitoring periods ending 2013 to 2026.
Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5) and nitrate: Arizona’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2020 to 2023, with EPA’s 2012 to 2019 file for earlier years.
Fluoride and chromium (total): EPA’s compliance monitoring file, samples taken from Aug. 27, 2014 to Feb. 13, 2019. Newer results are in the utility’s annual water quality report.
Above the legal limit1
Arsenic
Comes from the source
4.6ppb
Highest yearly average, 2020 to 2023
2023 average: 3.8 ppb
Averaged by year, the highest was 4.6 ppb, in 2022: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2023, the latest year on file, it averaged 3.8 ppb. EPA judges this limit at each sampling point, and recorded violations for arsenic at this utility in 2025 and 2026. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 5.5 ppb, in 2018.
What handles it
- NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
- NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
Above the health goal1
Lead
Comes from pipes, often your own
8.6ppb
90th percentile, 2026
In the latest period, 9 in 10 homes sampled were at or below 8.6 ppb, below EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.
What handles it
- NSF/ANSI 53 look for “Lead Reduction”
- NSF/ANSI 58 look for “Lead Reduction”
Below EPA’s limits5
Total trihalomethanes (TTHM)
Forms or is added in treatment
43.5ppb
Highest yearly average, 2020 to 2023
Averaged by year, the highest was 43.5 ppb, in 2023, below EPA’s legal limit of 80 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 57.5 ppb, in 2017.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Haloacetic acids (HAA5)
Forms or is added in treatment
20ppb
Highest yearly average, 2020 to 2023
Averaged by year, the highest was 20 ppb, in 2023, below EPA’s legal limit of 60 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 19.6 ppb, in 2014.
What handles it
No certification claim covers this compound yet.
Fluoride
Forms or is added in treatment
0.098ppm
Highest yearly average, 2014 to 2019
2019, one sample: 0.095 ppm
Averaged by year, the highest was 0.098 ppm, in 2017, below EPA’s legal limit of 4.0 ppm. In 2019, the latest year on file, its one sample was 0.095 ppm.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Nitrate
Comes from the source
0.24ppm
Highest yearly average, 2020 to 2023
2023 average: 0.24 ppm
Averaged by year, the highest was 0.24 ppm, in 2022, below EPA’s legal limit of 10 ppm. In 2023, the latest year on file, it averaged 0.24 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.31 ppm, in 2014.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
Chromium (total)
Comes from the source
2.3ppb
Highest yearly average, 2014 to 2019
2019: not found
Averaged by year, the highest was 2.3 ppb, in 2017, below EPA’s legal limit of 100 ppb. In 2019, the latest year on file, it wasn’t found in its one sample.
What handles it
- NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
- NSF/ANSI 53 look for “Chromium Reduction”
What handles it
A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”
- NSF/ANSI 53
Claims: Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction
For: Arsenic, Lead
Other certifiers’ wording: Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claims: Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction
For: Arsenic, Lead
Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)
At the tap, or for the whole house?
Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. How whole-house systems compare.
Filters with those claims on a certifier’s listing
Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Arsenic, Lead
Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic, Lead
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic, Lead
Brita Tahoe Pitcher with Elite Filter (OB60, OB06)
Pitcher
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 401checked Oct. 13, 2026
- IAPMO listing:NSF/ANSI 53checked Oct. 13, 2026
Certified for: Lead
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Surface Water Treatment Rule | Required treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR) | June 1, 2026 to June 30, 2026 | — | Archived |
| Arsenic | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2026 to March 31, 2026 | 0.02 MG/L | Archived |
| Arsenic | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2025 to Dec. 31, 2025 | 0.019 MG/L | Archived |
| Interim Enhanced Surface Water Treatment Rule | Too many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR) | May 1, 2023 to May 31, 2023 | — | Resolved |
| Interim Enhanced Surface Water Treatment Rule | Too many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR) | April 1, 2023 to April 30, 2023 | — | Resolved |
| Total organic carbon | Not enough organic matter was removed. It reacts with disinfectant to form byproducts.EPA: Treatment Technique Precursor Removal | Oct. 1, 2022 to Dec. 31, 2022 | 0.88 RATIO | Resolved |
| Total organic carbon | Not enough organic matter was removed. It reacts with disinfectant to form byproducts.EPA: Treatment Technique Precursor Removal | July 1, 2022 to Sept. 30, 2022 | 1.1 RATIO | Resolved |
| Interim Enhanced Surface Water Treatment Rule | Too many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR) | Jan. 1, 2017 to Jan. 31, 2017 | — | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 39 monitoring or reporting violations not shown. | ||||
What this report can’t tell you
Everything else. Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5) and nitrate results here are Arizona’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Fluoride and chromium (total) come from EPA’s file alone, which ends in 2019. City of Williams’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; CDC’s yearly averages for Arizona cover 2020 to 2023; EPA’s compliance samples are from Aug. 27, 2014 to Feb. 13, 2019.
Testing your own tap
The 3 labs Arizona certifies closest to the area City of Williams serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Inner Basin Environmental, LLC
Flagstaff, AZ · about 33 miles
Nortest Analytical
Flagstaff, AZ · about 33 miles
Bradshaw Mountain Environmental Inc.
Prescott Valley, AZ · about 55 miles
Sources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- CDC Environmental Public Health Tracking Network, yearly averages Arizona supplied to CDC, 2020 to 2023, read Oct. 8, 2026. TapBuff’s comparisons with EPA’s limits are its own, not CDC’s or Arizona’s.
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: Arizona Department of Health Services, Arizona certified commercial drinking water laboratories, read Oct. 17, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID AZ0403026. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on the 2 results above a lineWhat each one does to health, where it comes from, and the certification claim that addresses it.Start with Arsenic
- Get the utility’s own reportCity of Williams must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs