Is Johnston Municipal Water Supply Tap Water Safe? Quality Report

Water source: SWP
Ownership: Local government
Counties served: Polk

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

violations on file

still open

Violation	Type	Status	Period
MCL	Health-based	Resolved	2013-05-01 → 2013-05-31
MCL	Health-based	Resolved	2013-05-01 → 2013-05-31
MCL	Health-based	Resolved	2013-05-01 → 2013-05-31
MCL	Health-based	Resolved	2013-05-01 → 2013-05-31
MR	Monitoring	Resolved	2006-01-01 → 2006-03-31
MR	Monitoring	Resolved	2006-01-01 → 2006-03-31
MR	Monitoring	Resolved	2006-01-01 → 2006-03-31
MR	Monitoring	Resolved	2006-01-01 → 2006-03-31
MR	Monitoring	Resolved	2003-09-01 → 2003-09-30
MR	Monitoring	Resolved	2003-09-01 → 2003-09-30

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
Copper	173.6 µg/L 13% of the EPA limit 1300 µg/L worst single sample: 388 µg/L	170/180	SYR4	2012–2019
Dichloroacetic Acid	13.79 µg/L No EPA limit set worst single sample: 17.4 µg/L	132/132	SYR4	2012–2019
Trichloroacetic Acid	5.726 µg/L No EPA limit set worst single sample: 9.11 µg/L	132/132	SYR4	2012–2019
Chloroform	49.2 µg/L No EPA limit set worst single sample: 66.5 µg/L	131/132	SYR4	2012–2019
TTHM	74.3 µg/L 93% of the EPA limit 80 µg/L worst single sample: 96.3 µg/L	131/132	SYR4	2012–2019
Total Haloacetic Acids (HAA5)	25.2 µg/L 42% of the EPA limit 60 µg/L worst single sample: 31.4 µg/L	131/132	SYR4	2012–2019
Bromodichloromethane	19.595 µg/L No EPA limit set worst single sample: 21.7 µg/L	130/132	SYR4	2012–2019
Dibromochloromethane	11.4 µg/L No EPA limit set worst single sample: 14 µg/L	124/132	SYR4	2012–2019
Dibromoacetic Acid	3.03 µg/L No EPA limit set worst single sample: 4.78 µg/L	111/132	SYR4	2012–2019
Bromoform	3.197 µg/L No EPA limit set worst single sample: 3.88 µg/L	84/132	SYR4	2012–2019
Monochloroacetic Acid	9.469 µg/L No EPA limit set worst single sample: 12.6 µg/L	67/132	SYR4	2012–2019
Lead	11.395 µg/L 76% of the EPA limit 15 µg/L worst single sample: 54.1 µg/L	30/180	SYR4	2012–2019
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	19/19	LCR	2025
Lithium	33 µg/L No EPA limit set	8/8	UCMR-5	2025
Monobromoacetic Acid	3.6575 µg/L No EPA limit set worst single sample: 3.95 µg/L	6/132	SYR4	2012–2019

29 contaminants tested, none detected

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Utility contact

Contact: JOHNSTON, CITY OF
Phone: 515-278-0822
Email: [email protected]

Frequently asked questions about Johnston Municipal Water Supply

Is Johnston Municipal Water Supply tap water safe to drink?

EPA monitoring detected 15 contaminants in Johnston Municipal 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 Johnston Municipal Water Supply's water?

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

How many people does Johnston Municipal Water Supply serve?

Johnston Municipal Water Supply reports serving 24,897 people in Iowa, per its EPA record.

Has Johnston Municipal Water Supply had any water quality violations?

The EPA has 14 violations on file for Johnston Municipal Water Supply, of which 4 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.