Manganese Contamination

Manganese in Iowa Drinking Water

Ranked by max manganese detected (µg/L) · UCMR 4 data (2018–2020) · Data from EPA SDWIS & UCMR

Cities Tested

Over SMCL

10%

% Over SMCL

31.5 µg/L

State Avg

▼ 8% vs national

vs National

303

Health Violations

Analysis

Manganese in Iowa: what the data shows

Iowa has 52 cities with manganese data from the EPA's UCMR 4 program (2018–2020). Manganese exceeded the 50 µg/L EPA secondary MCL in 5 of those cities. The state average max detected level is 31.5 µg/L. Manganese occurs naturally in groundwater and surface water. Elevated levels are common in areas with iron-rich geology and in systems that draw from reservoirs with low dissolved oxygen. The secondary MCL of 50 µg/L is based on aesthetic concerns (taste, staining), but health-based guidelines suggest neurological effects at higher concentrations. Emerging research links chronic manganese exposure in drinking water to neurodevelopmental effects in children, including reduced IQ and behavioral issues. Oxidation filtration and water softeners are effective at removing manganese from household water.

Comparison

Cities exceeding 50 µg/L EPA Secondary MCL

Iowa

10%

5 of 52 cities

← ▼ 8% below national rate (better)

National avg

18%

729 of 4068 cities

City Map

Manganese data across Iowa

Each dot is a city with UCMR 4 manganese testing data. Cities where manganese exceeds the 50 µg/L EPA secondary MCL are highlighted. Size reflects population served.

Worst Offenders

Top 10 cities by manganese level in Iowa

Highest Manganese levels (µg/L)

All Cities

All Iowa cities ranked by manganese level

#	City	Level	Over SMCL?	Violations	Grade
1	Cedar Rapids	687.0 µg/L	Over SMCL	31	D
2	Muscatine	200.0 µg/L	Over SMCL	46	F
3	Ruthven	180.0 µg/L	Over SMCL	0	A-
4	Cedar Falls	100.0 µg/L	Over SMCL	4	A-
5	Marion	74.0 µg/L	Over SMCL	6	A-
6	Rock Valley	36.0 µg/L	No	13	B+
7	Clinton	35.0 µg/L	No	0	A-
8	Waverly	30.4 µg/L	No	2	B+
9	Waterloo	24.7 µg/L	No	3	A-
10	Fort Dodge	23.8 µg/L	No	19	D+
11	Carroll	20.0 µg/L	No	0	B
12	Centerville	20.0 µg/L	No	4	B+
13	North Liberty	15.0 µg/L	No	29	B-
14	Winterset	14.0 µg/L	No	20	A-
15	Sloan	14.0 µg/L	No	0	A
16	Sioux City	12.9 µg/L	No	14	B
17	Council Bluffs	12.7 µg/L	No	8	B+
18	Jefferson	12.0 µg/L	No	2	A
19	Newton	11.8 µg/L	No	2	A
20	Oskaloosa	11.3 µg/L	No	11	A-
21	Manning	9.0 µg/L	No	4	A-
22	Rockford	9.0 µg/L	No	1	A+
23	Storm Lake	8.0 µg/L	No	1	A-
24	Fayette	8.0 µg/L	No	0	A-
25	Coralville	7.0 µg/L	No	15	B
26	Ottumwa	6.4 µg/L	No	6	B+
27	Ainsworth	5.2 µg/L	No	1	A
28	Red Oak	5.1 µg/L	No	9	A-
29	Davenport	4.8 µg/L	No	2	C-
30	Moulton	4.1 µg/L	No	1	A-
31	Marshalltown	4.0 µg/L	No	4	A-
32	Mason City	3.1 µg/L	No	18	A-
33	Fort Madison	3.0 µg/L	No	6	A-
34	Ankeny	2.8 µg/L	No	15	B
35	Clive	2.4 µg/L	No	1	A
36	Johnston	2.3 µg/L	No	6	B+
37	Des Moines	2.1 µg/L	No	7	B+
38	Iowa City	2.0 µg/L	No	171	F
39	Dubuque	2.0 µg/L	No	30	F
40	Indianola	2.0 µg/L	No	7	A-
41	Burlington	1.0 µg/L	No	7	B+
42	West Des Moines	1.0 µg/L	No	1	B+
43	Spencer	1.0 µg/L	No	1	A
44	Spirit Lake	0.9 µg/L	No	4	A
45	Ames	0.8 µg/L	No	15	B+
46	Urbandale	0.8 µg/L	No	0	B+
47	Creston	0.7 µg/L	No	9	A-
48	Boone	0.7 µg/L	No	9	B
49	Altoona	0.6 µg/L	No	20	B+
50	Brooklyn	0.6 µg/L	No	10	A+
51	Waukee	0.4 µg/L	No	13	A-
52	Keokuk	0.4 µg/L	No	0	A-

FAQ

Frequently asked questions about manganese in Iowa

Is manganese in Iowa tap water harmful?

The EPA secondary MCL for manganese is 50 µg/L, set primarily for aesthetic reasons (taste, color, staining). 5 cities in Iowa exceed the secondary MCL. However, emerging research links chronic manganese exposure above 50–100 µg/L to neurodevelopmental effects in children, including reduced IQ.

How can I remove manganese from my drinking water?

Oxidation filtration (such as greensand or birm filters) is the most common and effective method for removing manganese from well water. Water softeners using ion exchange also work well. Standard carbon filters provide limited manganese removal. If your water has a metallic taste or brown/black discoloration, manganese may be the cause.

What causes high manganese in Iowa water?

Manganese occurs naturally in groundwater and surface water, particularly in areas with iron-rich geology. Low dissolved oxygen conditions (common in deep wells and reservoir bottom waters) increase manganese solubility. Industrial sources include mining, steel production, and battery manufacturing. Seasonal changes in reservoir water chemistry can cause manganese spikes.

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