Is Sioux City Water Supply Tap Water Safe? Quality Report

Water source: Ground water under surface influence
Ownership: Local government
Counties served: Woodbury

Compliance record

Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.

health-based violations

121

violations on file

still open

Violation	Type	Status	Period
MCL	Health-based	Resolved	2019-10-01 → 2019-12-31
MCL	Health-based	Resolved	2019-10-01 → 2019-12-31
MCL	Health-based	Resolved	2019-10-01 → 2019-12-31
MCL	Health-based	Resolved	2019-10-01 → 2019-12-31
MCL	Health-based	Resolved	2019-07-01 → 2019-09-30
MCL	Health-based	Resolved	2019-07-01 → 2019-09-30
MCL	Health-based	Resolved	2019-07-01 → 2019-09-30
MCL	Health-based	Resolved	2019-07-01 → 2019-09-30
MCL	Health-based	Resolved	2019-07-01 → 2019-09-30
TT	Health-based	Resolved	2017-03-06 → 2017-03-07

PFAS detected

PFAS are industrial “forever chemicals”. These are the EPA's latest nationwide test results (2023–2025).

Contaminant	Max	Detection rate	Period
Pfba	0.0092 µg/L	4/8	2024
PFBS	0.0210 µg/L	4/8	2024
Pfhxa	0.0330 µg/L	4/8	2024
PFHXS	0.0350 µg/L	4/8	2024
Pfpea	0.0220 µg/L	4/8	2024
Pfpes	0.0140 µg/L	4/8	2024
Pfhpa	0.0048 µg/L	3/8	2024
PFOA	0.0060 µg/L	2/8	2024
PFOS	0.0043 µg/L	2/8	2024

Other contaminants detected

Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of this system's samples — over 100% is worth reading, but is not by itself a violation. Where a single sample came in higher than that percentile, it is noted under the bar. Formal violations are listed separately.

Contaminant	Level vs EPA limit	Detection rate	Source	Period
Bromodichloromethane	27 µg/L No EPA limit set worst single sample: 35 µg/L	248/248	SYR4	2012–2019
Chloroform	63.95 µg/L No EPA limit set worst single sample: 90 µg/L	248/248	SYR4	2012–2019
Dibromochloromethane	12 µg/L No EPA limit set worst single sample: 16 µg/L	248/248	SYR4	2012–2019
TTHM	98.95 µg/L 124% of the EPA limit, at the 95th percentile of samples — 80 µg/L worst single sample: 140 µg/L	248/248	SYR4	2012–2019
Trichloroacetic Acid	21 µg/L No EPA limit set worst single sample: 31 µg/L	248/248	SYR4	2012–2019
Dichloroacetic Acid	19 µg/L No EPA limit set worst single sample: 29 µg/L	247/248	SYR4	2012–2019
Total Haloacetic Acids (HAA5)	43 µg/L 72% of the EPA limit 60 µg/L worst single sample: 59 µg/L	247/248	SYR4	2012–2019
Dibromoacetic Acid	3 µg/L No EPA limit set	228/248	SYR4	2012–2019
Copper	1200 µg/L 92% of the EPA limit 1300 µg/L worst single sample: 3800 µg/L	206/216	SYR4	2013–2019
Bromoform	1.615 µg/L No EPA limit set worst single sample: 2.3 µg/L	138/248	SYR4	2012–2019
Lead	12.95 µg/L 86% of the EPA limit 15 µg/L worst single sample: 230 µg/L	82/216	SYR4	2013–2019
Monochloroacetic Acid	3 µg/L No EPA limit set	23/248	SYR4	2012–2019
Lead	0.0020 mg/L 13% of the EPA limit 0.0150 mg/L	16/16	LCR	2025
cis-1,2-Dichloroethylene	0.8300 µg/L 1.2% of the EPA limit 70 µg/L worst single sample: 0.9000 µg/L	15/20	SYR4	2012–2019
Nitrate	2600 µg/L 26% of the EPA limit 10000 µg/L	8/30	SYR4	2012–2019
Lithium	240 µg/L No EPA limit set	8/8	UCMR-5	2024
Toluene	2.43 µg/L 0.2% of the EPA limit 1000 µg/L worst single sample: 2.5 µg/L	2/7	SYR4	2012–2018
Arsenic	2 µg/L 20% of the EPA limit 10 µg/L	1/2	SYR4	2014–2017
Carbon Tetrachloride	1 µg/L 20% of the EPA limit 5 µg/L	1/6	SYR4	2012–2018
Fluoride	660 µg/L 17% of the EPA limit 4000 µg/L	1/1	SYR4	2014

62 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAntimony, TotalAsbestosAtrazineBariumBenzeneBenzo(A)PyreneChlorobenzeneCadmiumChromiumCombined Radium (-226 And -228)DichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylbenzeneGlyphosateHfpo-DaLassoMercuryMonobromoacetic AcidNetfosaaNfdhaNmefosaaPfdaPfdoaPfeesaPfhpsPfmbaPfmpaPFNAPftaPftrdaPfunaPentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTrichloroethyleneVinyl ChlorideXylenes, TotalO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: SIOUX CITY WATER SUPPLY
Phone: 712-279-6150
Email: [email protected]

Frequently asked questions about Sioux City Water Supply

Is Sioux City Water Supply tap water safe to drink?

EPA monitoring detected 29 contaminants in Sioux City Water Supply's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.

What contaminants were detected in Sioux City Water Supply's water?

EPA monitoring detected Bromodichloromethane, Chloroform, Dibromochloromethane, TTHM, Trichloroacetic Acid, and others. The full list with the level and data source for each is above.

How many people does Sioux City Water Supply serve?

Sioux City Water Supply reports serving 85,791 people in Iowa, per its EPA record.

Has Sioux City Water Supply had any water quality violations?

The EPA has 121 violations on file for Sioux City Water Supply, of which 54 are health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.