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Sioux City Water Supply water quality report, rewritten

Serves
85,791
Connections
29,424
Water source
Groundwater influenced by surface water
Based in
Sioux City, IA
County
Woodbury
Owner
Local government
The 9 ZIP codes it serves

51101, 51102, 51103, 51104, 51105, 51106, 51107, 51108, 51111

PWSID IA9778054 · EPA data

Read this first

  • PFHxS (above the health goal) was found in four of 8 samples, highest 35 ppt. Above the 10 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.
  • PFOA (above the health goal) was found in two of 8 samples, highest 6.0 ppt. Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.
  • Copper (above the health goal) In the latest period, 9 in 10 homes sampled were at or below 1.9 ppm, above the 1.3 ppm action level.
  • PFOS (above the health goal) was found in two of 8 samples, highest 4.3 ppt. Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.
  • Lithium (above EPA’s health benchmark) was found in eight of 8 samples, highest 240 ppb. Above EPA’s health reference level of 10 ppb, a screening level rather than an enforceable limit.

5 health-based violations since 2016. Details are below.

What handles it

What was found

Highlighted: above the health goal, or EPA’s health benchmark where there is no goal. Circled: above the legal limit in at least one sample, or the action level. Every scale puts that line at its middle.

PFAS and lithium: EPA UCMR 5, samples taken from Oct. 16, 2023 to July 15, 2024. Each blue tick on a scale is one sample where it was found.

Lead and copper: EPA SDWIS monitoring periods ending 1992. The pointer marks the latest period; each blue tick is an earlier one.

NSF’s PFAS claims are tested to below 20 ppt. EPA’s limit is 10 ppt, and EPA says no certification yet shows a filter reaching its levels.

PFHxS (above the health goal)

Comes from the source

35 (above the legal limit in at least one sample)ppt

Highest of 8 samples; found in four

Above the 10 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.

What handles it

PFOA (above the health goal)

Comes from the source

6.0 (above the legal limit in at least one sample)ppt

Highest of 8 samples; found in two

Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.

What handles it

Copper (above the health goal)

Comes from pipes, often your own

1.9 (above the action level)ppm

90th percentile, 1992

In the latest period, 9 in 10 homes sampled were at or below 1.9 ppm, above the 1.3 ppm action level.

What handles it

PFOS (above the health goal)

Comes from the source

4.3 (above the legal limit in at least one sample)ppt

Highest of 8 samples; found in two

Above the 4.0 ppt legal limit in at least one sample. Compliance is judged on a running annual average, not one sample.

What handles it

240ppb

Highest of 8 samples; found in eight

Above EPA’s health reference level of 10 ppb, a screening level rather than an enforceable limit.

What handles it

No certification claim covers this compound yet.

Lead (above the health goal)

Comes from pipes, often your own

2.0ppb

90th percentile, 2023 to 2025

In the latest period, 9 in 10 homes sampled were at or below 2.0 ppb, below the 15 ppb action level. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.

What handles it

PFBS

Comes from the source

21ppt

Highest of 8 samples; found in four

Below EPA’s hazard index benchmark of 2,000 ppt. PFBS has no legal limit or health goal of its own.

What handles it

Also found, with no federal limit

EPA measured these PFAS to learn how often they occur. None has a legal limit or a health goal yet.

CompoundHighest sampleFound inCertification claim
PFHxA33 ppt4 of 8None covers it
PFPeA22 ppt4 of 8None covers it
PFPeS14 ppt4 of 8None covers it
PFBA9.2 ppt4 of 8None covers it
PFHpA4.8 ppt3 of 8NSF/ANSI 53: Total PFAS Reduction

Tested and not found

Below EPA’s minimum reporting level in every sample taken from Oct. 16, 2023 to July 15, 2024. Not found means not measured above that level, which is not the same as zero.

All 20 compounds tested and not found
  • 11Cl-PF3OUdS
  • 4:2 FTS
  • 6:2 FTS
  • 8:2 FTS
  • 9Cl-PF3ONS
  • ADONA
  • HFPO-DA (GenX)
  • NEtFOSAA
  • NFDHA
  • NMeFOSAA
  • PFDA
  • PFDoA
  • PFEESA
  • PFHpS
  • PFMBA
  • PFMPA
  • PFNA
  • PFTA
  • PFTrDA
  • PFUnA

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2019 to Dec. 31, 20190.084 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2019 to Sept. 30, 20190.083 MG/LResolved
EpichlorohydrinTreatment TechniquesMarch 6, 2017 to March 7, 2017—Resolved
EpichlorohydrinTreatment TechniquesNov. 25, 2016 to Nov. 26, 2016—Resolved
EpichlorohydrinTreatment TechniquesMay 19, 2016 to May 20, 2016—Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 2 monitoring or reporting violations not shown.

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: Total PFAS Reduction, PFOA Reduction, Copper Reduction, PFOS Reduction, Lead Reduction

    Other certifiers’ wording: Perfluorohexane Sulfonic Acid (PFHxS); Perfluorooctanoic Acid (PFOA); Perfluorooctane Sulfonate (PFOS)

    For: PFHxS, PFOA, Copper, PFOS, Lead

  • NSF/ANSI 58

    Claims: Perfluorooctanoic Acid (PFOA), Copper Reduction, Perfluorooctane Sulfonate (PFOS), Lead Reduction

    For: PFOA, Copper, PFOS, Lead

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.

Compare five-year costs

Filters with those claims on a certifier’s listing

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

What this report cannot tell you

  • Levels of everything else. Federal bulk data carries results for PFAS, lithium, lead and copper, and violations for the rest. Nitrate, arsenic, disinfection byproducts and other levels are in Sioux City Water Supply’s own annual report, which it must send you every year.
  • 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.
  • Anything after the latest data. SDWIS data is from 2026 Q2; UCMR 5 samples are from Oct. 16, 2023 to July 15, 2024.

Other Iowa utilities

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Sources

What to do next

  • Read up on the 6 marked results

    What each one does to health, where it comes from, and the certification claim that addresses it.

    Start with PFHxS

  • Get the utility’s own report

    Sioux City Water Supply must send you a water quality report every year. It lists nitrate, arsenic and byproduct levels this page cannot.

    How to read it

  • Test your own tap for lead

    Your 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 filters

    What the filters certified for these results cost over five years, cartridges included.

    Compare five-year costs