Chlorate Contamination

Chlorate in North Carolina Drinking Water

Ranked by max chlorate detected (µg/L) · UCMR 3 data (2013–2015) · Data from EPA SDWIS & UCMR

Cities Tested

Over HA

73%

% Over HA

770.7 µg/L

State Avg

▲ 14% vs national

vs National

362

Health Violations

Analysis

Chlorate in North Carolina: what the data shows

North Carolina has 89 cities with chlorate data from the EPA's UCMR 3 program (2013–2015). Chlorate exceeded the 210 µg/L EPA lifetime health advisory in 65 of those cities. The state average max detected level is 770.7 µg/L. Chlorate is a disinfection byproduct that forms when chlorine dioxide or hypochlorite solutions are used to disinfect drinking water. It is most common in systems that use chlorine dioxide for taste-and-odor control or that store hypochlorite for extended periods. There is no federal MCL — the EPA lifetime health advisory is 210 µg/L. Chlorate can interfere with thyroid function by blocking iodide uptake, an effect of particular concern for pregnant women, infants, and people with thyroid conditions. Reverse osmosis and ion exchange (anion-specific) are effective at removing chlorate; standard activated carbon filters provide only modest reduction.

Comparison

Cities exceeding 210 µg/L EPA lifetime HA (no MCL)

North Carolina

73%

65 of 89 cities

→ ▲ 14% above national rate (worse)

National avg

59%

1866 of 3166 cities

City Map

Chlorate data across North Carolina

Each dot is a city with UCMR 3 chlorate testing data. Cities where chlorate exceeds the 210 µg/L EPA lifetime health advisory are highlighted. Size reflects population served.

Worst Offenders

Top 10 cities by chlorate level in North Carolina

Highest Chlorate levels (µg/L)

All Cities

All North Carolina cities ranked by chlorate level

#	City	Level	Over HA?	Violations	Grade
1	Fayetteville	22000.0 µg/L	Over HA	392	F
2	Raleigh	4000.0 µg/L	Over HA	241	F
3	Lexington	2100.0 µg/L	Over HA	14	B-
4	Bellarthur	2000.0 µg/L	Over HA	3	B-
5	Goldsboro	1860.0 µg/L	Over HA	11	F
6	New Bern	1740.0 µg/L	Over HA	4	B+
7	Elizabethtown	1600.0 µg/L	Over HA	1	B+
8	Asheboro	1300.0 µg/L	Over HA	8	F
9	Mebane	1200.0 µg/L	Over HA	10	B+
10	Laurinburg	1165.1 µg/L	Over HA	0	C
11	Camp Lejeune	1122.8 µg/L	Over HA	10	A-
12	Rocky Mount	1110.0 µg/L	Over HA	17	C
13	Fuquay-Varina	1100.0 µg/L	Over HA	34	F
14	Pinehurst	1000.0 µg/L	Over HA	5	C-
15	Clayton	970.0 µg/L	Over HA	50	D
16	Elizabeth City	927.0 µg/L	Over HA	2	A-
17	Wilson Mills	921.0 µg/L	Over HA	3	B-
18	Mount Airy	833.0 µg/L	Over HA	0	B
19	Raeford	820.0 µg/L	Over HA	16	F
20	Greensboro	750.0 µg/L	Over HA	29	F
21	Statesville	750.0 µg/L	Over HA	37	F
22	Forest City	660.0 µg/L	Over HA	1	B-
23	Carrboro	650.0 µg/L	Over HA	0	A
24	Kinston	620.0 µg/L	Over HA	4	C-
25	Havelock	581.0 µg/L	Over HA	20	B+
26	Lillington	530.0 µg/L	Over HA	4	B-
27	Longview	529.0 µg/L	Over HA	0	A-
28	Monroe	526.0 µg/L	Over HA	10	B-
29	Maxton	509.8 µg/L	Over HA	12	C
30	Kill Devil Hill	469.0 µg/L	Over HA	1	A-
31	King	457.0 µg/L	Over HA	12	B+
32	Newport	452.0 µg/L	Over HA	31	F
33	Thomasville	450.0 µg/L	Over HA	0	A-
34	Warrenton	448.1 µg/L	Over HA	5	B
35	Holly Springs	440.0 µg/L	Over HA	8	C-
36	Tarboro	440.0 µg/L	Over HA	49	F
37	Kannapolis	432.0 µg/L	Over HA	16	C-
38	Burlington	420.0 µg/L	Over HA	33	F
39	Nashville	419.8 µg/L	Over HA	36	F
40	Rockingham	390.0 µg/L	Over HA	15	C
41	Burgaw	385.8 µg/L	Over HA	21	F
42	Boone	382.0 µg/L	Over HA	33	F
43	Roxboro	379.0 µg/L	Over HA	9	A-
44	Jacksonville	375.0 µg/L	Over HA	22	F
45	Greenville	370.0 µg/L	Over HA	7	C-
46	Roanoke Rapids	366.0 µg/L	Over HA	17	B
47	Cherry Point	343.0 µg/L	Over HA	3	A-
48	Apex	340.0 µg/L	Over HA	40	F
49	Erwin	330.0 µg/L	Over HA	0	B+
50	Lilesville	323.0 µg/L	Over HA	16	D
51	Butner	310.0 µg/L	Over HA	25	B
52	Concord	306.0 µg/L	Over HA	37	F
53	Durham	300.0 µg/L	Over HA	94	F
54	High Point	290.0 µg/L	Over HA	2	B-
55	Deep Run	270.0 µg/L	Over HA	0	B+
56	Asheville	260.0 µg/L	Over HA	12	F
57	Denver	250.0 µg/L	Over HA	10	C-
58	Mooresville	240.0 µg/L	Over HA	22	F
59	Clemmons	230.0 µg/L	Over HA	0	A-
60	Henderson	230.0 µg/L	Over HA	25	F
61	Hudson	223.8 µg/L	Over HA	2	A-
62	Wilmington	220.0 µg/L	Over HA	22	F
63	Harrisburg	220.0 µg/L	Over HA	28	F
64	Sanford	214.0 µg/L	Over HA	31	F
65	Highlands	211.0 µg/L	Over HA	25	F
66	Conover	200.0 µg/L	No	6	F
67	Maple	190.0 µg/L	No	4	B+
68	Leland	188.9 µg/L	No	11	C
69	Granite Falls	173.8 µg/L	No	4	B+
70	Taylorsville	170.0 µg/L	No	7	B
71	Hickory	165.0 µg/L	No	11	F
72	Morganton	160.0 µg/L	No	2	B+
73	Gastonia	150.0 µg/L	No	102	F
74	Rutherfordton	150.0 µg/L	No	7	B-
75	Cary	130.0 µg/L	No	9	F
76	Salisbury	126.0 µg/L	No	27	F
77	Oak Island	112.0 µg/L	No	1	B
78	Hillsborough	100.0 µg/L	No	9	C-
79	Smithfield	66.7 µg/L	No	9	C+
80	Hamlet	66.0 µg/L	No	20	F
81	Washington	63.7 µg/L	No	2	B+
82	Wilson	53.0 µg/L	No	7	C+
83	Mocksville	50.0 µg/L	No	19	C
84	Kings Mountain	49.0 µg/L	No	5	B
85	Lincolnton	42.0 µg/L	No	0	D+
86	Shelby	37.6 µg/L	No	2	A
87	Reidsville	34.4 µg/L	No	36	F
88	N Wilkesboro	27.0 µg/L	No	4	B+
89	Hendersonville	26.0 µg/L	No	36	F

FAQ

Frequently asked questions about chlorate in North Carolina

Is chlorate in North Carolina tap water dangerous?

Chlorate has no federal MCL. The EPA lifetime health advisory is 210 µg/L. 65 cities in North Carolina exceed this level. Chlorate can interfere with thyroid iodide uptake, which is a particular concern for infants, pregnant women, and people with hypothyroidism.

Where does chlorate in North Carolina water come from?

Chlorate is a byproduct of chlorine-based disinfectants — particularly chlorine dioxide and hypochlorite (bleach) solutions. Levels tend to be higher in systems that use chlorine dioxide for taste-and-odor treatment or store sodium hypochlorite at high concentrations or for long periods. Levels vary seasonally with disinfectant use.

How can I reduce chlorate exposure?

Reverse osmosis is the most effective home treatment for chlorate, typically removing 80–95%. Anion exchange systems also work but require regeneration. Standard activated carbon filters provide only limited chlorate reduction. Boiling does NOT remove chlorate.

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