HAA5 Contamination

HAA5 in Wisconsin Drinking Water

Ranked by average HAA5 concentration (µg/L) · UCMR 4 data (2018–2020) · Data from EPA SDWIS & UCMR

Cities Tested

Exceeds Limit

% Exceeds Limit

6.7 µg/L

State Avg

▼ 1% vs national

vs National

388

Health Violations

Analysis

HAA5 in Wisconsin: what the data shows

Wisconsin has 85 cities with HAA5 monitoring data from the EPA's UCMR 4 program (2018–2020). Haloacetic acids (HAA5) form when chlorine-based disinfectants react with natural organic matter in water. The state average is 6.7 µg/L — better than the 15.5 µg/L national average. No cities currently exceed the 60 µg/L EPA MCL. HAA5 is a group of five chlorinated and brominated acetic acids. Long-term exposure above the MCL is associated with increased cancer risk and adverse reproductive outcomes. The EPA classifies total HAA5 as a probable human carcinogen at elevated concentrations. Activated carbon filtration (especially granular or block carbon) is effective at reducing HAA5. Running water through a refrigerator filter or letting it sit in an open pitcher for 30 minutes also helps, as some HAA5 species are volatile. Boiling does not remove disinfection byproducts and may concentrate them.

Comparison

Cities exceeding 60 µg/L EPA MCL

Wisconsin

0 of 85 cities

← ▼ 1% below national rate (better)

National avg

23 of 4420 cities

City Map

HAA5 data across Wisconsin

Each dot is a city with UCMR 4 HAA5 testing data. Cities where average HAA5 exceeded the 60 µg/L EPA MCL are highlighted. Size reflects population served.

Worst Offenders

Top 10 cities by haa5 level in Wisconsin

Highest HAA5 levels (µg/L)

All Cities

All Wisconsin cities ranked by haa5 level

#	City	Level	Exceeds?	Violations	Grade
1	Wisconsin Rapids	32.6 µg/L	No	6	B-
2	Marinette	28.4 µg/L	No	0	A-
3	Neenah	26.6 µg/L	No	6	C+
4	Two Rivers	23.2 µg/L	No	5	C-
5	Manitowoc	22.1 µg/L	No	0	B+
6	South Milwaukee	21.7 µg/L	No	0	A-
7	Grand Chute	20.9 µg/L	No	2	A
8	Port Washington	19.6 µg/L	No	6	B+
9	Menasha	19.1 µg/L	No	1	B+
10	De Pere	19.1 µg/L	No	38	B
11	Green Bay	18.8 µg/L	No	74	D+
12	Franklin	18.6 µg/L	No	10	B
13	Racine	17.2 µg/L	No	4	C+
14	Pleasant Prairie	16.7 µg/L	No	7	B+
15	Sheboygan	15.7 µg/L	No	1	A-
16	Caledonia	13.9 µg/L	No	1	B
17	Oak Creek	13.8 µg/L	No	5	B
18	Kenosha	13.8 µg/L	No	11	D
19	Wausau	12.9 µg/L	No	24	C
20	Superior	12.3 µg/L	No	17	F
21	Sheboygan Falls	10.0 µg/L	No	5	B-
22	Eau Claire	9.4 µg/L	No	18	D+
23	Glendale	9.1 µg/L	No	1	A-
24	Marshfield	8.8 µg/L	No	9	C-
25	Whitefish Bay	8.6 µg/L	No	0	B+
26	Cudahy	7.5 µg/L	No	0	B+
27	Oshkosh	7.3 µg/L	No	0	A
28	Cornell	6.2 µg/L	No	6	A
29	Fond Du Lac	5.8 µg/L	No	51	F
30	Stevens Point	5.5 µg/L	No	14	C+
31	Weston	5.1 µg/L	No	0	B+
32	Watertown	4.2 µg/L	No	10	D
33	North Fond Du Lac	4.1 µg/L	No	6	B
34	Middleton	3.9 µg/L	No	3	C+
35	West Allis	3.8 µg/L	No	0	A-
36	Onalaska	3.8 µg/L	No	2	A-
37	Brookfield	3.7 µg/L	No	32	C-
38	Chippewa Falls	3.6 µg/L	No	12	D+
39	Shorewood	3.4 µg/L	No	1	A-
40	Brown Deer	3.2 µg/L	No	5	A
41	Portage	3.2 µg/L	No	9	B
42	Menomonee Falls	3.2 µg/L	No	6	B+
43	Greendale	3.2 µg/L	No	1	A-
44	Grafton	3.2 µg/L	No	12	C+
45	West Bend	2.9 µg/L	No	11	F
46	Wauwatosa	2.8 µg/L	No	1	B+
47	Waukesha	2.7 µg/L	No	320	D
48	New Berlin	2.5 µg/L	No	14	B
49	Milwaukee	2.5 µg/L	No	2	A
50	La Crosse	2.4 µg/L	No	34	F
51	Cedarburg	2.3 µg/L	No	1	B+
52	Oconomowoc	2.2 µg/L	No	13	B
53	Plover	2.2 µg/L	No	9	B+
54	Kaukauna	2.1 µg/L	No	9	B+
55	Appleton	2.1 µg/L	No	4	B+
56	Whitewater	2.0 µg/L	No	22	C+
57	Hartford	2.0 µg/L	No	2	B+
58	Waterford	2.0 µg/L	No	13	B
59	Saukville	1.7 µg/L	No	0	B
60	Hudson	1.6 µg/L	No	4	B
61	Sussex	1.5 µg/L	No	70	D+
62	Beaver Dam	1.4 µg/L	No	11	A-
63	Germantown	1.3 µg/L	No	8	B-
64	Little Chute	1.2 µg/L	No	1	B+
65	Madison	1.1 µg/L	No	14	F
66	Beloit	1.1 µg/L	No	2	B+
67	Coon Valley	1.0 µg/L	No	2	B+
68	Mount Horeb	1.0 µg/L	No	1	A
69	Waterloo	1.0 µg/L	No	5	A-
70	Amherst	0.9 µg/L	No	1	B
71	Janesville	0.9 µg/L	No	12	B
72	Fitchburg	0.9 µg/L	No	0	A
73	Platteville	0.8 µg/L	No	11	D+
74	Cottage Grove	0.8 µg/L	No	2	A-
75	Menomonie	0.7 µg/L	No	30	F
76	Omro	0.7 µg/L	No	1	A-
77	New Lisbon	0.6 µg/L	No	3	B+
78	Waunakee	0.6 µg/L	No	11	B-
79	River Falls	0.6 µg/L	No	14	C+
80	Fort Atkinson	0.5 µg/L	No	14	A-
81	Baraboo	0.5 µg/L	No	0	B
82	Sun Prairie	0.4 µg/L	No	4	A
83	Viroqua	0.3 µg/L	No	2	A-
84	Stoughton	0.1 µg/L	No	4	B+
85	Monroe	0.1 µg/L	No	9	A-

FAQ

Frequently asked questions about haa5 in Wisconsin

What is HAA5 and why does it appear in Wisconsin tap water?

HAA5 (haloacetic acids) are disinfection byproducts that form when chlorine reacts with naturally occurring organic matter in source water. They are a normal byproduct of the disinfection process that makes water safe to drink. No cities in Wisconsin currently exceed the 60 µg/L EPA MCL. The state average is 6.7 µg/L.

How can I reduce HAA5 exposure from Wisconsin drinking water?

Activated carbon filters (granular or block) effectively reduce HAA5. Refrigerator filters and under-sink carbon systems are convenient options. Unlike lead or PFAS, HAA5 levels can also be reduced by letting water stand in an open container, as some species evaporate. Boiling does NOT remove HAA5 and can concentrate them by reducing water volume.

Which Wisconsin cities have the highest HAA5 levels?

The cities with the highest average HAA5 concentrations in Wisconsin are: Wisconsin Rapids (32.6 µg/L), Marinette (28.4 µg/L), Neenah (26.6 µg/L), Two Rivers (23.2 µg/L), Manitowoc (22.1 µg/L). Note: this data is from UCMR 4 testing (2018–2020) and may not reflect current levels.

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