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Why Dwid

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
400 people
Connections
118
Water source
Groundwater
Based in
Why, AZ
County
Pima
Owner
Private
The ZIP code it serves

85321

The short answer

1 result is above EPA’s legal limit, and 1 more is above the health goal. The worst: Copper, above the action level. 11 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2020 to 2022.

Arsenic, total trihalomethanes (TTHM), nitrate and haloacetic acids (HAA5): 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 Dec. 13, 2014 to Oct. 23, 2017. Newer results are in the utility’s annual water quality report.

Above the legal limit1

Copper

Comes from pipes, often your own

Above the action level

5.9ppm

90th percentile, 2020 to 2022

In the latest period, 9 in 10 homes sampled were at or below 5.9 ppm, above EPA’s action level of 1.3 ppm.

What handles it

Above the health goal1

Arsenic

Comes from the source

Above the health goal

5.2ppb

Highest yearly average, 2020 to 2023

Averaged by year, the highest was 5.2 ppb, in 2023: below EPA’s legal limit of 10 ppb, but above its health goal of zero. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 18.5 ppb, in 2015, and EPA recorded violations in 2012, 2016, 2017 and 2018.

What handles it

  • NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
  • NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”

Below EPA’s limits5

Fluoride

Forms or is added in treatment

Below EPA’s limits

3.1ppm

Highest yearly average, 2014 to 2017

Averaged by year, the highest was 3.1 ppm, in 2017, below EPA’s legal limit of 4.0 ppm. That was also the latest year on file.

What handles it

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

40.2ppb

Highest yearly average, 2020 to 2023

2023 average: 4.6 ppb

Averaged by year, the highest was 40.2 ppb, in 2021, below EPA’s legal limit of 80 ppb. In 2023, the latest year on file, it averaged 4.6 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 17.8 ppb, in 2016.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Nitrate

Comes from the source

Below EPA’s limits

3.9ppm

Highest yearly average, 2020 to 2023

2023 average: 3.4 ppm

Averaged by year, the highest was 3.9 ppm, in 2020, below EPA’s legal limit of 10 ppm. In 2023, the latest year on file, it averaged 3.4 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 3.9 ppm, in 2015.

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

Below EPA’s limits

28ppb

Highest yearly average, 2014 to 2017

Averaged by year, the highest was 28 ppb, in 2017, below EPA’s legal limit of 100 ppb. That was also the latest year on file.

What handles it

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

6.4ppb

Highest yearly average, 2020 to 2023

Averaged by year, the highest was 6.4 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 4.1 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Lead

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: Copper Reduction, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Copper, Arsenic

    Other certifiers’ wording: Arsenic (III) (50 ppb influent level)

  • NSF/ANSI 58

    Claims: Copper Reduction, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Copper, Arsenic

    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

Compare five-year costs

The best reverse osmosis systems, ranked

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2018 to Dec. 31, 20180.013 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2018 to Sept. 30, 20180.013 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2018 to June 30, 20180.02 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2018 to March 31, 20180.02 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2017 to Dec. 31, 20170.012 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2017 to Sept. 30, 20170.011 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2017 to June 30, 20170.013 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2017 to March 31, 20170.013 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2016 to Dec. 31, 20160.013 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2016 to Sept. 30, 20160.013 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2016 to March 31, 20160.022 MG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 52 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Arsenic, total trihalomethanes (TTHM), nitrate and haloacetic acids (HAA5) 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. Why Dwid’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 Dec. 13, 2014 to Oct. 23, 2017.

Testing your own tap

Why Dwid’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab Arizona certifies.

No lab Arizona certifies is within 75 miles of the area Why Dwid serves on the state’s list. Some take samples by mail; the state’s page lists them all.

All 49 certified labs for Arizona

Sources

PWSID AZ0410118. Rebuilt from EPA data on Oct. 18, 2026.

Also in Pima County

All Arizona utilities

What to do next