Arsenic Contamination

Arsenic in Washington Drinking Water

Ranked by arsenic violation count · Data from EPA SDWIS & UCMR

226

Cities Tested

226

Has Violations

100%

% Has Violations

11.5 violations

State Avg

▼ 0% vs national

vs National

261

Health Violations

Analysis

Arsenic in Washington: what the data shows

Washington has 226 cities with arsenic-related violations on record. Arsenic contamination is a federal MCL violation at levels above 10 µg/L (10 ppb). The state has 226 cities with at least one arsenic violation. Arsenic enters drinking water primarily through erosion of natural deposits, particularly in western states with arsenite-bearing geology. Industrial sources include mining runoff, glass manufacturing, and semiconductor production. Groundwater systems are significantly more likely to have arsenic issues than surface water systems. Long-term arsenic exposure above the MCL increases the risk of bladder, lung, and skin cancer, as well as cardiovascular disease and diabetes. Reverse osmosis and specialized arsenic-removal media are the most effective point-of-use treatment options.

Comparison

Cities exceeding 10 µg/L EPA MCL

Washington

100%

226 of 226 cities

← = Exactly at national rate

National avg

100%

5489 of 5489 cities

City Map

Arsenic data across Washington

Each dot is a city with arsenic violation data. Cities with at least one arsenic-related violation are highlighted. Size reflects population served.

Worst Offenders

Top 10 cities by arsenic level in Washington

Highest Arsenic levels (violations)

All Cities

All Washington cities ranked by arsenic level

#	City	Level	Violations?	Violations	Grade
1	Port Orchard	245 violations	Yes	753	F
2	Coupeville	200 violations	Yes	448	F
3	Freeland	119 violations	Yes	129	D
4	Ridgefield	113 violations	Yes	0	D
5	Wellpinit	110 violations	Yes	103	D+
6	Napavine	103 violations	Yes	104	D
7	Seattle	91 violations	Yes	138	F
8	Yakima	82 violations	Yes	162	F
9	Mount Vernon	62 violations	Yes	191	F
10	Ferndale	60 violations	Yes	110	F
11	Nespelem	54 violations	Yes	40	D+
12	Lacey	52 violations	Yes	125	F
13	Tonasket	50 violations	Yes	134	D
14	Shelton	46 violations	Yes	158	F
15	Arlington	44 violations	Yes	83	F
16	Tacoma	41 violations	Yes	232	F
17	Lynden	32 violations	Yes	235	F
18	Stanwood	31 violations	Yes	31	D
19	Wapato	30 violations	Yes	11	F
20	Poulsbo	29 violations	Yes	95	F
21	Moses Lake	29 violations	Yes	132	F
22	Othello	27 violations	Yes	102	D
23	Cle Elum	24 violations	Yes	105	D
24	Spokane	22 violations	Yes	56	F
25	Oak Harbor	22 violations	Yes	105	F
26	Sequim	21 violations	Yes	64	F
27	Woodland	19 violations	Yes	16	F
28	Colville	19 violations	Yes	44	D
29	Port Ludlow	19 violations	Yes	27	C+
30	Kennewick	17 violations	Yes	78	F
31	Warden	17 violations	Yes	9	D+
32	Vancouver	16 violations	Yes	36	F
33	Fall City	16 violations	Yes	18	B-
34	Bellingham	14 violations	Yes	54	F
35	Gig Harbor	14 violations	Yes	62	F
36	Raymond	14 violations	Yes	76	F
37	Toppenish	14 violations	Yes	12	F
38	Union	14 violations	Yes	52	D
39	Pasco	13 violations	Yes	137	D
40	Maple Falls	13 violations	Yes	35	D+
41	Olympia	11 violations	Yes	66	F
42	Snohomish	11 violations	Yes	11	D
43	Loon Lake	11 violations	Yes	14	F
44	Friday Harbor	11 violations	Yes	153	F
45	Snoqualmie Pass	11 violations	Yes	4	B+
46	Westport	11 violations	Yes	4	D+
47	Marysville	10 violations	Yes	12	D
48	Cashmere	10 violations	Yes	21	F
49	Mattawa	10 violations	Yes	33	C
50	Everett	9 violations	Yes	16	D
51	Puyallup	9 violations	Yes	124	F
52	Brewster	9 violations	Yes	7	D
53	South Bend	9 violations	Yes	83	D+
54	Republic	9 violations	Yes	181	D
55	Neah Bay	9 violations	Yes	22	D
56	Wenatchee	8 violations	Yes	41	D
57	Newport	8 violations	Yes	14	D+
58	Forks	8 violations	Yes	8	D
59	Lopez Island	8 violations	Yes	28	F
60	Silverdale	7 violations	Yes	17	F
61	Clarkston	7 violations	Yes	16	B+
62	Ellensburg	7 violations	Yes	19	D
63	Cathlamet	7 violations	Yes	66	C
64	Marshall	7 violations	Yes	22	D
65	Electric City	7 violations	Yes	11	A
66	Custer	7 violations	Yes	12	C+
67	Deming	7 violations	Yes	23	D
68	Auburn	6 violations	Yes	18	D+
69	Hoquiam	6 violations	Yes	6	B-
70	Montesano	6 violations	Yes	17	F
71	Connell	6 violations	Yes	22	C+
72	Eastsound	6 violations	Yes	29	F
73	Black Diamond	6 violations	Yes	13	C-
74	Davenport	6 violations	Yes	14	A-
75	Dallesport	6 violations	Yes	2	C+
76	Lummi Island	6 violations	Yes	32	D+
77	Richland	5 violations	Yes	7	C+
78	Bremerton	5 violations	Yes	13	C
79	Sammamish	5 violations	Yes	6	C-
80	Port Angeles	5 violations	Yes	19	F
81	Kelso	5 violations	Yes	15	F
82	Monroe	5 violations	Yes	4	C
83	Yelm	5 violations	Yes	12	D+
84	West Richland	5 violations	Yes	99	F
85	Ocean Park	5 violations	Yes	6	B+
86	College Place	5 violations	Yes	23	D
87	Prosser	5 violations	Yes	42	C+
88	Waverly	5 violations	Yes	25	D
89	Bridgeport	5 violations	Yes	47	C
90	Pe Ell	5 violations	Yes	16	B-
91	Camano Island	5 violations	Yes	9	C
92	Spokane Valley	4 violations	Yes	10	C-
93	Port Townsend	4 violations	Yes	15	F
94	Aberdeen	4 violations	Yes	10	D
95	Carlsborg	4 violations	Yes	2	B-
96	Chehalis	4 violations	Yes	12	F
97	Selah	4 violations	Yes	4	B
98	Grandview	4 violations	Yes	5	D+
99	Leavenworth	4 violations	Yes	20	C
100	Ephrata	4 violations	Yes	13	D
101	Elma	4 violations	Yes	5	B-
102	Belfair	4 violations	Yes	36	C-
103	Medical Lake	4 violations	Yes	9	B-
104	Okanogan	4 violations	Yes	11	B+
105	Quinault	4 violations	Yes	3	D
106	Washtucna	4 violations	Yes	6	C+
107	Kent	3 violations	Yes	31	F
108	Renton	3 violations	Yes	11	D+
109	Bothell	3 violations	Yes	7	F
110	Woodinville	3 violations	Yes	1	A-
111	Buckley	3 violations	Yes	5	D+
112	Walla Walla	3 violations	Yes	84	D
113	Issaquah	3 violations	Yes	10	C-
114	Cheney	3 violations	Yes	5	A-
115	Maple Valley	3 violations	Yes	7	C+
116	Enumclaw	3 violations	Yes	1	B+
117	Chelan	3 violations	Yes	18	D
118	Vashon	3 violations	Yes	24	F
119	Sultan	3 violations	Yes	33	B
120	Omak	3 violations	Yes	5	D
121	Long Beach	3 violations	Yes	15	B
122	Chewelah	3 violations	Yes	7	B+
123	Mossyrock	3 violations	Yes	14	C-
124	Allyn	3 violations	Yes	4	A-
125	Sumas	3 violations	Yes	17	A-
126	Mabton	3 violations	Yes	1	A-
127	Falls City	3 violations	Yes	2	B+
128	Oakville	3 violations	Yes	4	F
129	Onalaska	3 violations	Yes	2	C+
130	Tekoa	3 violations	Yes	5	C
131	Waterville	3 violations	Yes	10	B
132	Packwood	3 violations	Yes	2	A-
133	George	3 violations	Yes	3	A-
134	Acme	3 violations	Yes	4	A-
135	Ravensdale	3 violations	Yes	22	B-
136	Ronald	3 violations	Yes	5	C+
137	Federal Way	2 violations	Yes	2	B
138	Joint Base Lewis-Mcchord	2 violations	Yes	3	B+
139	Kirkland	2 violations	Yes	4	D+
140	Mead	2 violations	Yes	3	B-
141	Liberty Lake	2 violations	Yes	2	A
142	North Bend	2 violations	Yes	7	B+
143	Benton City	2 violations	Yes	17	F
144	Moxee	2 violations	Yes	2	B
145	Hoodsport	2 violations	Yes	5	C+
146	Everson	2 violations	Yes	8	B+
147	White Salmon	2 violations	Yes	9	C+
148	Carson	2 violations	Yes	0	C-
149	Winlock	2 violations	Yes	4	B+
150	Zillah	2 violations	Yes	11	D+
151	Tenino	2 violations	Yes	2	B+
152	Rock Island	2 violations	Yes	5	A-
153	Stevenson	2 violations	Yes	1	C+
154	Mccleary	2 violations	Yes	0	A
155	Clinton	2 violations	Yes	8	C
156	Bow	2 violations	Yes	7	A-
157	Ion	2 violations	Yes	2	A
158	Snoqualmie	2 violations	Yes	10	A-
159	Rochester	2 violations	Yes	5	A-
160	Ritzville	2 violations	Yes	6	A-
161	Tahola	2 violations	Yes	15	D
162	Pateros	2 violations	Yes	2	B+
163	Lapush	2 violations	Yes	2	B+
164	Burbank	2 violations	Yes	47	D
165	Rockford	2 violations	Yes	0	B
166	Sprague	2 violations	Yes	2	B+
167	Redmond	1 violations	Yes	4	B-
168	Tumwater	1 violations	Yes	24	D+
169	Lakewood	1 violations	Yes	5	B+
170	Pullman	1 violations	Yes	0	B+
171	Edmonds	1 violations	Yes	0	A-
172	Longview	1 violations	Yes	0	B+
173	Spanaway	1 violations	Yes	9	C+
174	Centralia	1 violations	Yes	5	B-
175	East Wenatchee	1 violations	Yes	19	B
176	Washougal	1 violations	Yes	2	B+
177	Quincy	1 violations	Yes	52	D+
178	Sumner	1 violations	Yes	0	A-
179	Airway	1 violations	Yes	2	B
180	Goldendale	1 violations	Yes	15	B-
181	Fircrest	1 violations	Yes	4	A-
182	Union Gap	1 violations	Yes	5	A
183	Blaine	1 violations	Yes	8	A
184	Granger	1 violations	Yes	3	A
185	Lake Forest Park	1 violations	Yes	15	D+
186	Colfax	1 violations	Yes	4	B
187	Eatonville	1 violations	Yes	2	A-
188	Oroville	1 violations	Yes	7	A-
189	Fox Island	1 violations	Yes	3	B+
190	Malaga	1 violations	Yes	6	A
191	Rainier	1 violations	Yes	1	A-
192	Ilwaco	1 violations	Yes	4	A
193	Goldbar	1 violations	Yes	1	A
194	Nooksack	1 violations	Yes	5	A
195	Adna	1 violations	Yes	9	A
196	Darrington	1 violations	Yes	4	D
197	Joyce	1 violations	Yes	10	A-
198	Kittitas	1 violations	Yes	1	A
199	Mesa	1 violations	Yes	15	C+
200	Morton	1 violations	Yes	3	B-
201	Toledo	1 violations	Yes	2	A-
202	Waitsburg	1 violations	Yes	1	A
203	Newman Lake	1 violations	Yes	6	A+
204	Sedro Woolley	1 violations	Yes	1	A
205	Graham	1 violations	Yes	5	A
206	Bingen	1 violations	Yes	0	A-
207	Entiat	1 violations	Yes	0	A-
208	Lake Tapps	1 violations	Yes	6	B-
209	Ashford	1 violations	Yes	3	A-
210	Palouse	1 violations	Yes	5	A
211	Pouslbo	1 violations	Yes	4	A
212	Wilkeson	1 violations	Yes	0	A
213	North Bonneville	1 violations	Yes	0	A-
214	Rosalia	1 violations	Yes	7	A-
215	Twisp	1 violations	Yes	6	A
216	Vashion Island	1 violations	Yes	2	B+
217	Cusick	1 violations	Yes	7	B+
218	Chinook	1 violations	Yes	23	A-
219	Suquamish	1 violations	Yes	4	B+
220	Startup	1 violations	Yes	4	A
221	Littlerock	1 violations	Yes	3	A
222	Randle	1 violations	Yes	0	A
223	Albion	1 violations	Yes	7	A
224	Greenbank	1 violations	Yes	9	B-
225	Bucoda	1 violations	Yes	5	B+
226	South Cle Elum	1 violations	Yes	0	A-

FAQ

Frequently asked questions about arsenic in Washington

Is arsenic in Washington tap water a concern?

Yes — 226 cities in Washington have arsenic-related violations on record. The EPA MCL for arsenic is 10 µg/L. Even at levels below the MCL, long-term arsenic exposure has been linked to cancer and cardiovascular disease.

How can I remove arsenic from my drinking water in Washington?

Reverse osmosis (RO) systems are the most effective at removing arsenic, typically reducing it by 90% or more. Specialized arsenic-removal media (such as iron-based adsorption filters) are also highly effective. Standard carbon filters and pitcher filters do NOT effectively remove arsenic. If your water comes from a private well, have it tested for arsenic.

Where does arsenic in Washington water come from?

Arsenic enters drinking water primarily through natural erosion of arsenic-bearing rock formations. It is most common in groundwater systems in the western United States, parts of the Midwest, and New England. Industrial sources include mining, smelting, and agricultural pesticide residues. Groundwater sources are far more likely to contain arsenic than surface water.

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