Lithium Contamination

Lithium in California Drinking Water

Ranked by max lithium detected (µg/L) · UCMR 5 data (2023–2025) · Data from EPA SDWIS & UCMR

250

Cities Tested

250

Detected

100%

% Detected

44.8 µg/L

State Avg

▼ 0% vs national

vs National

624

Health Violations

Analysis

Lithium in California: what the data shows

California has 250 cities with lithium data from the EPA's UCMR 5 program (2023–2025). Lithium was detected in 250 of those cities. There is currently no federal MCL or health advisory for lithium — the state average max detected level is 44.8 µg/L. Nationally, lithium is detected in roughly 28% of sampled water systems. Lithium occurs naturally in groundwater, particularly in arid western states, and is concentrated in some surface waters near industrial discharge or geothermal sources. UCMR 5 added lithium monitoring in 2023, providing the first systematic national snapshot of public-water lithium levels. At therapeutic doses (administered as a medication), lithium is used to treat bipolar disorder. Chronic low-dose exposure from drinking water has been associated in some studies with effects on thyroid function and possibly mood. The most protective state guidance value is around 60 µg/L. Reverse osmosis and ion exchange are effective removal methods.

Comparison

Cities exceeding No federal MCL or HA

California

100%

250 of 250 cities

← = Exactly at national rate

National avg

100%

2808 of 2808 cities

City Map

Lithium data across California

Each dot is a city with UCMR 5 lithium testing data. Detected cities are shown — there is no federal limit, though some states use 60 µg/L as a screening level. Size reflects population served.

Worst Offenders

Top 10 cities by lithium level in California

Highest Lithium levels (µg/L)

All Cities

All California cities ranked by lithium level

#	City	Level	Detected?	Violations	Grade
1	Sacramento	474.0 µg/L	Detected	425	F
2	Blythe	159.0 µg/L	Detected	143	D
3	Mammoth Lakes	153.0 µg/L	Detected	24	B
4	Ventura	140.0 µg/L	Detected	21	D+
5	Mariposa	113.0 µg/L	Detected	71	C
6	Needles	108.0 µg/L	Detected	45	F
7	Coarsegold	106.0 µg/L	Detected	24	C-
8	Running Springs	106.0 µg/L	Detected	3	B
9	China Lake	104.0 µg/L	Detected	8	A
10	Brentwood	102.0 µg/L	Detected	91	F
11	Los Angeles	100.0 µg/L	Detected	94	F
12	Santa Rosa	96.0 µg/L	Detected	177	F
13	Rosemead	91.9 µg/L	Detected	17	C-
14	Downey	88.6 µg/L	Detected	14	B
15	Soquel	88.0 µg/L	Detected	1	A
16	San Dimas	87.0 µg/L	Detected	6	B-
17	San Jose	81.3 µg/L	Detected	142	F
18	Holtville	81.1 µg/L	Detected	66	B-
19	Barstow	79.0 µg/L	Detected	66	F
20	Imperial	78.8 µg/L	Detected	36	C+
21	Camarillo	78.5 µg/L	Detected	4	B
22	Oroville	76.0 µg/L	Detected	7	C-
23	St. Helena	75.0 µg/L	Detected	29	C+
24	Heber	74.4 µg/L	Detected	15	A
25	Ojai	74.1 µg/L	Detected	35	C-
26	Patterson	74.0 µg/L	Detected	35	B+
27	Lompoc	72.2 µg/L	Detected	18	C
28	Fillmore	70.0 µg/L	Detected	13	B-
29	Scotts Valley	69.5 µg/L	Detected	11	B-
30	El Centro	69.0 µg/L	Detected	14	C-
31	Santa Barbara	67.9 µg/L	Detected	52	F
32	Lomita	67.4 µg/L	Detected	1	A-
33	Irvine	67.2 µg/L	Detected	84	F
34	Mojave	66.5 µg/L	Detected	114	D
35	Tracy	66.2 µg/L	Detected	45	C
36	Trabuco Canyon	65.9 µg/L	Detected	2	A-
37	Montebello	65.7 µg/L	Detected	5	B
38	La Canada Flintridge	65.7 µg/L	Detected	4	A
39	Imperial Beach	65.5 µg/L	Detected	1	A
40	Salinas	65.1 µg/L	Detected	639	F
41	San Diego	65.0 µg/L	Detected	43	F
42	Pasadena	64.2 µg/L	Detected	92	F
43	Roseville	62.6 µg/L	Detected	11	B
44	Santa Ynez	62.2 µg/L	Detected	14	A-
45	Brawley	62.0 µg/L	Detected	5	A-
46	Inglewood	61.4 µg/L	Detected	3	A-
47	Anaheim	61.0 µg/L	Detected	8	C+
48	Cerritos	61.0 µg/L	Detected	0	B
49	Bell Gardens	61.0 µg/L	Detected	0	B
50	Glendale	60.4 µg/L	Detected	0	A-
51	Ridgecrest	60.3 µg/L	Detected	26	A-
52	Santa Fe Springs	60.0 µg/L	Detected	1	B+
53	San Clemente	60.0 µg/L	Detected	3	A-
54	Arroyo Grande	60.0 µg/L	Detected	93	F
55	Calexico	59.0 µg/L	Detected	7	B-
56	Norwalk	59.0 µg/L	Detected	1	A-
57	Alhambra	58.0 µg/L	Detected	7	A-
58	Torrance	58.0 µg/L	Detected	0	A-
59	Compton	58.0 µg/L	Detected	8	B
60	Signal Hill	58.0 µg/L	Detected	6	B
61	Pacific Grove	57.5 µg/L	Detected	15	B-
62	San Juan Capistrano	57.4 µg/L	Detected	5	B+
63	La Habra	56.3 µg/L	Detected	0	A-
64	Highland	56.2 µg/L	Detected	3	B+
65	Brea	56.2 µg/L	Detected	0	A
66	Paramount	56.0 µg/L	Detected	0	A-
67	Vernon	56.0 µg/L	Detected	3	A
68	Corona	55.1 µg/L	Detected	81	D
69	Vandenberg Sfb	55.1 µg/L	Detected	8	A
70	Greenfield	54.3 µg/L	Detected	17	B
71	Encinitas	54.1 µg/L	Detected	55	F
72	Long Beach	54.0 µg/L	Detected	2	C
73	Covina	54.0 µg/L	Detected	10	B
74	Santa Cruz	54.0 µg/L	Detected	38	F
75	Huntington Park	54.0 µg/L	Detected	3	B+
76	Altadena	53.6 µg/L	Detected	2	B+
77	Goleta	53.5 µg/L	Detected	11	B
78	Newhall	53.1 µg/L	Detected	1	B+
79	La Canada	53.0 µg/L	Detected	5	B
80	Avalon	52.9 µg/L	Detected	1	A-
81	Carlsbad	52.5 µg/L	Detected	0	A+
82	Vista	52.0 µg/L	Detected	0	A-
83	San Marcos	52.0 µg/L	Detected	27	D
84	Fallbrook	51.6 µg/L	Detected	3	A
85	Manhattan Beach	51.4 µg/L	Detected	1	A-
86	Hawthorne	51.3 µg/L	Detected	3	B
87	Rancho Santa Margarita	50.1 µg/L	Detected	0	A
88	Walnut	50.1 µg/L	Detected	1	A-
89	Temecula	50.0 µg/L	Detected	12	C+
90	Murphys	50.0 µg/L	Detected	11	B+
91	California City	49.7 µg/L	Detected	22	A-
92	Lynwood	49.0 µg/L	Detected	0	B+
93	Poway	48.7 µg/L	Detected	0	A-
94	Firebaugh	48.6 µg/L	Detected	89	D
95	La Habra Heights	48.5 µg/L	Detected	0	A
96	Del Mar	48.1 µg/L	Detected	3	B-
97	Laguna Beach	48.0 µg/L	Detected	2	B
98	Rowland Heights	48.0 µg/L	Detected	0	B+
99	Santee	47.0 µg/L	Detected	14	B
100	Beverly Hills	47.0 µg/L	Detected	18	B
101	Rosamond	46.9 µg/L	Detected	205	F
102	Twentynine Palms	46.5 µg/L	Detected	70	B+
103	Paso Robles	46.2 µg/L	Detected	42	F
104	Woodland	46.1 µg/L	Detected	52	F
105	Castaic	46.1 µg/L	Detected	17	F
106	Santa Paula	46.0 µg/L	Detected	5	A-
107	Vacaville	45.0 µg/L	Detected	26	F
108	Lake Forest	45.0 µg/L	Detected	38	B-
109	La Crescenta	45.0 µg/L	Detected	3	B+
110	Oxnard	44.4 µg/L	Detected	49	F
111	San Bernardino	44.0 µg/L	Detected	192	F
112	El Segundo	44.0 µg/L	Detected	0	A-
113	Los Banos	43.6 µg/L	Detected	29	B
114	Escondido	43.0 µg/L	Detected	10	B
115	Laguna Hills	43.0 µg/L	Detected	1	B+
116	Colusa	41.9 µg/L	Detected	6	C-
117	Solvang	41.1 µg/L	Detected	6	B
118	Cotati	41.0 µg/L	Detected	9	A-
119	Marina	40.9 µg/L	Detected	4	A+
120	Borrego Springs	40.8 µg/L	Detected	2	A+
121	Dixon	40.5 µg/L	Detected	2	A
122	Castroville	40.2 µg/L	Detected	86	D+
123	San Bruno	40.0 µg/L	Detected	0	A+
124	Valley Center	40.0 µg/L	Detected	15	F
125	Sonoma	40.0 µg/L	Detected	5	B-
126	Newman	40.0 µg/L	Detected	3	A-
127	Tehachapi	39.9 µg/L	Detected	96	F
128	Rancho Santa Fe	39.8 µg/L	Detected	3	A-
129	Perris	39.0 µg/L	Detected	0	A
130	Lake Elsinore	39.0 µg/L	Detected	8	A
131	Rohnert Park	39.0 µg/L	Detected	21	F
132	Gustine	39.0 µg/L	Detected	4	B+
133	Paicines	38.7 µg/L	Detected	9	B-
134	Santa Ana	38.5 µg/L	Detected	8	C
135	Redding	38.4 µg/L	Detected	49	F
136	Oceanside	38.0 µg/L	Detected	2	A-
137	Tustin	37.9 µg/L	Detected	8	B
138	Davis	37.3 µg/L	Detected	47	B+
139	Carpinteria	37.3 µg/L	Detected	5	A
140	Costa Mesa	37.3 µg/L	Detected	2	A-
141	Riverside	37.0 µg/L	Detected	13	C
142	Oak View	37.0 µg/L	Detected	12	B+
143	Camp Pendleton	36.9 µg/L	Detected	13	B
144	La Palma	36.7 µg/L	Detected	0	A-
145	Westminster	36.6 µg/L	Detected	2	A-
146	Buena Park	36.5 µg/L	Detected	1	B+
147	Placentia	36.4 µg/L	Detected	0	B+
148	Newport Beach	36.2 µg/L	Detected	4	B+
149	Fountain Valley	36.1 µg/L	Detected	0	A
150	Huntington Beach	36.0 µg/L	Detected	5	C-
151	Ramona	36.0 µg/L	Detected	36	C
152	El Verano	36.0 µg/L	Detected	0	B+
153	Norco	35.9 µg/L	Detected	39	F
154	Rancho Cordova	35.5 µg/L	Detected	115	F
155	San Joaquin	35.5 µg/L	Detected	13	A
156	Seal Beach	35.5 µg/L	Detected	0	A-
157	Orange	35.3 µg/L	Detected	3	B
158	Fullerton	35.0 µg/L	Detected	8	B
159	Santa Monica	34.8 µg/L	Detected	0	B
160	Garden Grove	34.7 µg/L	Detected	2	B
161	Discovery Bay	34.0 µg/L	Detected	3	A+
162	Gonzales	33.4 µg/L	Detected	53	F
163	Williams	32.3 µg/L	Detected	3	A+
164	Truckee	32.0 µg/L	Detected	7	A-
165	Soledad	32.0 µg/L	Detected	28	C+
166	Boulder Creek	32.0 µg/L	Detected	119	F
167	Lakeside	31.0 µg/L	Detected	0	A-
168	Port Hueneme	29.7 µg/L	Detected	0	B+
169	Hollister	29.0 µg/L	Detected	132	F
170	Spring Valley	28.9 µg/L	Detected	4	B
171	Quartz Hill	28.1 µg/L	Detected	1	A-
172	Chula Vista	28.0 µg/L	Detected	1	B+
173	Watsonville	27.3 µg/L	Detected	74	F
174	Templeton	27.3 µg/L	Detected	1	A
175	Buellton	27.3 µg/L	Detected	2	B+
176	Villa Park	27.1 µg/L	Detected	1	A-
177	Winters	27.0 µg/L	Detected	1	A+
178	South Lake Tahoe	26.3 µg/L	Detected	15	C
179	La Mesa	26.0 µg/L	Detected	0	A+
180	Kelseyville	26.0 µg/L	Detected	36	B-
181	Morgan Hill	25.5 µg/L	Detected	92	F
182	Clearlake	25.0 µg/L	Detected	5	B+
183	Wildomar	24.0 µg/L	Detected	11	A-
184	Susanville	23.9 µg/L	Detected	34	A-
185	Yucca Valley	23.0 µg/L	Detected	7	A-
186	Nuevo	23.0 µg/L	Detected	6	B+
187	Pittsburg	22.9 µg/L	Detected	0	A
188	Apple Valley	22.9 µg/L	Detected	57	D
189	Crestline	22.2 µg/L	Detected	9	C+
190	Maywood	21.8 µg/L	Detected	3	A-
191	Alpine	21.4 µg/L	Detected	25	C-
192	Delano	21.1 µg/L	Detected	67	B
193	Modesto	21.0 µg/L	Detected	76	D
194	Edwards Afb	20.8 µg/L	Detected	8	A-
195	Atascadero	20.7 µg/L	Detected	1	B
196	Bakersfield	20.6 µg/L	Detected	690	F
197	Aptos	20.3 µg/L	Detected	9	A-
198	Redlands	20.0 µg/L	Detected	2	B
199	El Cajon	20.0 µg/L	Detected	24	B+
200	Arnold	20.0 µg/L	Detected	2	B-
201	Rio Vista	19.0 µg/L	Detected	3	A+
202	Kirkwood	19.0 µg/L	Detected	0	A
203	Citrus Heights	18.0 µg/L	Detected	2	A
204	Lakeport	18.0 µg/L	Detected	14	C-
205	Palm Desert	17.7 µg/L	Detected	12	C+
206	Hidden Valley Lake	17.3 µg/L	Detected	1	A+
207	Pleasanton	16.8 µg/L	Detected	3	B-
208	Victorville	16.5 µg/L	Detected	1	B+
209	Sebastopol	16.3 µg/L	Detected	18	B-
210	Hemet	16.2 µg/L	Detected	31	B-
211	Los Osos	16.1 µg/L	Detected	0	B+
212	Banning	16.0 µg/L	Detected	15	B-
213	Ceres	15.7 µg/L	Detected	129	F
214	Guadalupe	15.6 µg/L	Detected	0	A
215	Santa Maria	15.1 µg/L	Detected	36	F
216	Calabasas	15.0 µg/L	Detected	14	A-
217	Oakley	15.0 µg/L	Detected	60	D
218	Big Bear Lake	14.5 µg/L	Detected	1	B+
219	Helendale	14.5 µg/L	Detected	22	A-
220	Lamont	14.1 µg/L	Detected	40	B+
221	Skyforest	14.1 µg/L	Detected	0	A-
222	Alturas	13.8 µg/L	Detected	11	B+
223	Joshua Tree	13.7 µg/L	Detected	3	A-
224	Bolinas	13.6 µg/L	Detected	49	A-
225	Daly City	13.0 µg/L	Detected	4	A
226	Nipomo	13.0 µg/L	Detected	1	A
227	Tahoe City	13.0 µg/L	Detected	11	B+
228	Rio Linda	12.9 µg/L	Detected	2	A-
229	Sonora	12.5 µg/L	Detected	25	D+
230	Moorpark	12.0 µg/L	Detected	1	A-
231	Pala	12.0 µg/L	Detected	30	C-
232	Porterville	11.6 µg/L	Detected	74	F
233	Orland	11.2 µg/L	Detected	5	A
234	Adelanto	11.1 µg/L	Detected	13	C
235	Santa Clara	11.0 µg/L	Detected	5	B
236	Gilroy	11.0 µg/L	Detected	28	C+
237	Grand Terrace	11.0 µg/L	Detected	1	B
238	Fort Irwin	11.0 µg/L	Detected	60	B+
239	Pismo Beach	10.8 µg/L	Detected	4	A-
240	Hesperia	10.2 µg/L	Detected	2	B
241	Corning	10.2 µg/L	Detected	17	B-
242	San Luis Obispo	10.0 µg/L	Detected	27	F
243	Ripon	9.9 µg/L	Detected	10	A-
244	Westlake Village	9.8 µg/L	Detected	8	F
245	West Covina	9.8 µg/L	Detected	25	F
246	Cutten	9.5 µg/L	Detected	5	A+
247	Pomona	9.3 µg/L	Detected	6	C+
248	Mountain View	9.3 µg/L	Detected	3	A
249	San Bernardin0	9.1 µg/L	Detected	0	A-
250	Wasco	9.1 µg/L	Detected	26	B+

FAQ

Frequently asked questions about lithium in California

Is lithium in California tap water harmful?

Lithium has no federal MCL or health advisory. Some state agencies use 60 µg/L as a screening level. 250 cities in California had detectable lithium in UCMR 5 testing. Therapeutic lithium doses (used to treat bipolar disorder) are far higher than typical drinking-water levels, but chronic low-level exposure has been studied for potential thyroid and mood effects.

Where does lithium in tap water come from?

Lithium occurs naturally in groundwater, especially in arid western states with lithium-bearing geology (parts of Nevada, California, North Carolina, Texas). It can also enter water from industrial sources such as battery manufacturing, ceramics, and lithium-mining wastewater. Geothermal hot springs are another natural source.

How can I remove lithium from my drinking water?

Reverse osmosis is highly effective at removing lithium, typically reducing it by 90% or more. Ion exchange systems and distillation also work well. Standard activated carbon filters are NOT effective against lithium. If you rely on a private well in a lithium-rich geological area, consider testing.

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