1,4-Dioxane Contamination

1,4-Dioxane in New York Drinking Water

Ranked by max 1,4-dioxane detected (µg/L) · UCMR 3 data (2013–2015) · Data from EPA SDWIS & UCMR

Cities Tested

Over HA

70%

% Over HA

2.76 µg/L

State Avg

▲ 35% vs national

vs National

630

Health Violations

Analysis

1,4-Dioxane in New York: what the data shows

New York has 46 cities with 1,4-dioxane data from the EPA's UCMR 3 program (2013–2015). 1,4-Dioxane was detected above the 0.35 µg/L EPA health advisory in 32 of those cities. The state average max detected level is 2.76 µg/L. 1,4-Dioxane is a synthetic industrial chemical used as a solvent stabilizer. It enters water supplies primarily from industrial discharge and contaminated groundwater plumes near manufacturing sites, landfills, and military bases. It is highly mobile in groundwater and resistant to biodegradation. The EPA classifies 1,4-dioxane as a likely human carcinogen. Long-term exposure is associated with liver and kidney damage. Advanced oxidation processes (AOP) are the most effective treatment; conventional water treatment and standard carbon filters are generally ineffective against 1,4-dioxane.

Comparison

Cities exceeding 0.35 µg/L EPA HA (no MCL)

New York

70%

32 of 46 cities

→ ▲ 35% above national rate (worse)

National avg

35%

394 of 1124 cities

City Map

1,4-Dioxane data across New York

Each dot is a city with UCMR 3 1,4-dioxane testing data. Cities where 1,4-dioxane exceeds the 0.35 µg/L EPA health advisory are highlighted. Size reflects population served.

Worst Offenders

Top 10 cities by 1,4-dioxane level in New York

Highest 1,4-Dioxane levels (µg/L)

All Cities

All New York cities ranked by 1,4-dioxane level

#	City	Level	Over HA?	Violations	Grade
1	Oyster Bay (T)	34.00 µg/L	Over HA	14	B-
2	Hempstead (T)	10.00 µg/L	Over HA	14	D
3	Hempstead (T)	10.00 µg/L	Over HA	9	F
4	Hempstead (V)	4.50 µg/L	Over HA	1	A-
5	Smithtown (T)	4.34 µg/L	Over HA	11	D
6	Smithtown (T)	4.34 µg/L	Over HA	5	C+
7	Smithtown (T)	4.34 µg/L	Over HA	5	B+
8	Smithtown (T)	4.34 µg/L	Over HA	5	B
9	Smithtown (T)	4.34 µg/L	Over HA	6	B+
10	Smithtown (T)	4.34 µg/L	Over HA	7	B-
11	Smithtown (T)	4.34 µg/L	Over HA	3	C
12	Smithtown (T)	4.34 µg/L	Over HA	11	B-
13	Smithtown (T)	4.34 µg/L	Over HA	3	A-
14	Garden City (V)	3.90 µg/L	Over HA	5	A-
15	New Hyde Park (V)	3.90 µg/L	Over HA	1	A
16	Endicott (V)	3.60 µg/L	Over HA	0	A-
17	Hempstead (T)	1.50 µg/L	Over HA	5	A-
18	Great Neck Estates (V)	1.24 µg/L	Over HA	2	A+
19	Great Neck Estates (V)	1.24 µg/L	Over HA	2	A+
20	Great Neck Estates (V)	1.24 µg/L	Over HA	2	A+
21	Great Neck Estates (V)	1.24 µg/L	Over HA	2	A+
22	Great Neck Estates (V)	1.24 µg/L	Over HA	2	A+
23	Great Neck Estates (V)	1.24 µg/L	Over HA	2	A+
24	Great Neck Estates (V)	1.24 µg/L	Over HA	2	A+
25	Westbury (V)	1.10 µg/L	Over HA	2	A-
26	Hempstead (T)	0.92 µg/L	Over HA	3	B
27	Oyster Bay (T)	0.90 µg/L	Over HA	2	A
28	Roslyn (V)	0.86 µg/L	Over HA	1	A
29	Johnson City (V)	0.73 µg/L	Over HA	2	A-
30	Mineola (V)	0.65 µg/L	Over HA	1	A-
31	Clarkstown (T)	0.50 µg/L	Over HA	11	B-
32	De Witt (T)	0.50 µg/L	Over HA	6	A-
33	Elma (T)	0.31 µg/L	No	0	A+
34	Rockville Center (V)	0.21 µg/L	No	5	A
35	Glenville (T)	0.17 µg/L	No	0	A
36	Vestal (T)	0.12 µg/L	No	2	A-
37	Yonkers (C)	0.11 µg/L	No	2	B+
38	Glen Cove (C)	0.11 µg/L	No	4	B+
39	Ramapo (T)	0.11 µg/L	No	19	C+
40	Sea Cliff (V)	0.10 µg/L	No	0	A+
41	Batavia (C)	0.09 µg/L	No	0	A+
42	Greenwood Lake (V)	0.09 µg/L	No	9	A-
43	New York (C)	0.08 µg/L	No	11	A-
44	Poughkeepsie (T)	0.08 µg/L	No	0	A-
45	Binghamton (C)	0.08 µg/L	No	5	A-
46	Cohoes (C)	0.07 µg/L	No	5	B+

FAQ

Frequently asked questions about 1,4-dioxane in New York

Is 1,4-dioxane in New York tap water dangerous?

1,4-Dioxane is classified by the EPA as a likely human carcinogen. There is no federal MCL, but the EPA health advisory is 0.35 µg/L. 32 cities in New York exceed the health advisory level. Long-term exposure is associated with liver and kidney damage.

How can I remove 1,4-dioxane from my drinking water?

1,4-Dioxane is one of the most difficult contaminants to remove from water. Standard carbon filters and conventional water treatment are generally ineffective. Advanced oxidation processes (AOP) used by water utilities are the most reliable. At the household level, some high-end reverse osmosis systems may provide partial reduction, but no standard point-of-use filter is certified for 1,4-dioxane removal.

Where does 1,4-dioxane come from in New York water?

1,4-Dioxane is a synthetic industrial chemical primarily used as a solvent stabilizer in chlorinated solvent degreasing operations. It enters water from industrial discharge, contaminated groundwater plumes near manufacturing sites, landfills, and military bases. It is highly water-soluble, does not bind to soil, and resists natural biodegradation, making it a persistent groundwater contaminant.

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