Chlorate Contamination
Chlorate in New York Drinking Water
Ranked by max chlorate detected (µg/L) · UCMR 3 data (2013–2015) · Data from EPA SDWIS & UCMR
200
Cities Tested
117
Over HA
59%
% Over HA
303.9 µg/L
State Avg
▲ 1% vs national
vs National
594
Health Violations
Analysis
Chlorate in New York: what the data shows
New York has 200 cities with chlorate data from the EPA's UCMR 3 program (2013–2015). Chlorate exceeded the 210 µg/L EPA lifetime health advisory in 117 of those cities. The state average max detected level is 303.9 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)
New York
59%
117 of 200 cities
→ ▲ 1% above national rate (worse)
National avg
58%
1812 of 3098 cities
City Map
Chlorate data across New York
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 New York
All Cities
All New York cities ranked by chlorate level
| # | City | Level | Level | Over HA? | Violations | Grade |
|---|---|---|---|---|---|---|
| 1 | Philipstown (T) | 1223.8 µg/L | Over HA | 5 | B- | |
| 2 | Oyster Bay (T) | 1200.0 µg/L | Over HA | 14 | B- | |
| 3 | Clarkstown (T) | 1000.0 µg/L | Over HA | 11 | B- | |
| 4 | Huntington (T) | 900.0 µg/L | Over HA | 11 | D | |
| 5 | Hempstead (T) | 870.0 µg/L | Over HA | 14 | D | |
| 6 | Stewart Manor (V) | 870.0 µg/L | Over HA | 5 | A- | |
| 7 | Endicott (V) | 780.2 µg/L | Over HA | 0 | A- | |
| 8 | Saratoga Sprngs (C) | 697.0 µg/L | Over HA | 3 | A- | |
| 9 | North Hempstead (T) | 680.0 µg/L | Over HA | 9 | F | |
| 10 | Buffalo (C) | 650.0 µg/L | Over HA | 2 | A- | |
| 11 | Amherst (T) | 650.0 µg/L | Over HA | 0 | A | |
| 12 | Cheektowaga (T) | 650.0 µg/L | Over HA | 0 | A | |
| 13 | Clarence (T) | 650.0 µg/L | Over HA | 0 | A | |
| 14 | Concord (T) | 650.0 µg/L | Over HA | 8 | B- | |
| 15 | Depew (V) | 650.0 µg/L | Over HA | 0 | A | |
| 16 | Evans (T) | 650.0 µg/L | Over HA | 0 | A | |
| 17 | Lackawanna (C) | 650.0 µg/L | Over HA | 0 | A | |
| 18 | Lancaster (V) | 650.0 µg/L | Over HA | 0 | A | |
| 19 | Sloan (V) | 650.0 µg/L | Over HA | 0 | A | |
| 20 | Tonawanda (C) | 650.0 µg/L | Over HA | 0 | A | |
| 21 | Batavia (C) | 634.0 µg/L | Over HA | 0 | A+ | |
| 22 | Port Chester (V) | 630.0 µg/L | Over HA | 0 | A | |
| 23 | Rye Brook (V) | 630.0 µg/L | Over HA | 0 | A | |
| 24 | Rye (T) | 630.0 µg/L | Over HA | 0 | A | |
| 25 | Olean (C) | 590.0 µg/L | Over HA | 1 | B | |
| 26 | Middletown (C) | 570.0 µg/L | Over HA | 3 | A | |
| 27 | Brownville (T) | 540.0 µg/L | Over HA | 3 | A- | |
| 28 | Canajoharie (V) | 510.0 µg/L | Over HA | 3 | A | |
| 29 | Kiryas Joel (V) | 500.0 µg/L | Over HA | 3 | D+ | |
| 30 | New Windsor (T) | 483.0 µg/L | Over HA | 14 | D+ | |
| 31 | Ithaca (C) | 478.0 µg/L | Over HA | 11 | B+ | |
| 32 | Great Neck Estates (V) | 469.0 µg/L | Over HA | 2 | A+ | |
| 33 | Great Neck Plaza (V) | 469.0 µg/L | Over HA | 2 | A+ | |
| 34 | Great Neck (V) | 469.0 µg/L | Over HA | 2 | A+ | |
| 35 | Kensington (V) | 469.0 µg/L | Over HA | 2 | A+ | |
| 36 | Kings Point (V) | 469.0 µg/L | Over HA | 2 | A+ | |
| 37 | Saddle Rock (V) | 469.0 µg/L | Over HA | 2 | A+ | |
| 38 | Thomaston (V) | 469.0 µg/L | Over HA | 2 | A+ | |
| 39 | Poughkeepsie (T) | 450.0 µg/L | Over HA | 0 | A- | |
| 40 | Warwick (T) | 443.0 µg/L | Over HA | 58 | D+ | |
| 41 | Tuxedo (T) | 443.0 µg/L | Over HA | 12 | B+ | |
| 42 | Newburgh (T) | 440.0 µg/L | Over HA | 50 | F | |
| 43 | Worcester (T) | 420.0 µg/L | Over HA | 1 | A- | |
| 44 | Colonie (T) | 400.0 µg/L | Over HA | 1 | A+ | |
| 45 | Plattsburgh (C) | 400.0 µg/L | Over HA | 1 | A- | |
| 46 | Nyack (V) | 397.0 µg/L | Over HA | 3 | B | |
| 47 | South Nyack (V) | 397.0 µg/L | Over HA | 3 | B | |
| 48 | Brookhaven (T) | 386.0 µg/L | Over HA | 3 | C | |
| 49 | East Hampton (T) | 386.0 µg/L | Over HA | 3 | A- | |
| 50 | Islip (T) | 386.0 µg/L | Over HA | 7 | B- | |
| 51 | Smithtown (T) | 386.0 µg/L | Over HA | 5 | B+ | |
| 52 | Southampton (T) | 386.0 µg/L | Over HA | 5 | B | |
| 53 | Southold (T) | 386.0 µg/L | Over HA | 11 | B- | |
| 54 | Riverhead (T) | 386.0 µg/L | Over HA | 5 | C+ | |
| 55 | Babylon (T) | 386.0 µg/L | Over HA | 6 | B+ | |
| 56 | Syracuse (C) | 380.0 µg/L | Over HA | 29 | C+ | |
| 57 | Clifton Park (T) | 360.0 µg/L | Over HA | 4 | D | |
| 58 | Rochester (C) | 350.0 µg/L | Over HA | 3 | B | |
| 59 | Brighton (T) | 350.0 µg/L | Over HA | 5 | C+ | |
| 60 | Chili (T) | 350.0 µg/L | Over HA | 1 | B | |
| 61 | Churchville (V) | 350.0 µg/L | Over HA | 1 | B | |
| 62 | Clarkson (T) | 350.0 µg/L | Over HA | 1 | B | |
| 63 | East Rochester (X) | 350.0 µg/L | Over HA | 1 | B | |
| 64 | Fairport (V) | 350.0 µg/L | Over HA | 1 | B | |
| 65 | Gates (T) | 350.0 µg/L | Over HA | 1 | B | |
| 66 | Greece (T) | 350.0 µg/L | Over HA | 1 | B | |
| 67 | Hamlin (T) | 350.0 µg/L | Over HA | 1 | B | |
| 68 | Henrietta (T) | 350.0 µg/L | Over HA | 1 | B | |
| 69 | Honeoye Falls (V) | 350.0 µg/L | Over HA | 1 | B | |
| 70 | Irondequoit (T) | 350.0 µg/L | Over HA | 1 | C+ | |
| 71 | Kendall (T) | 350.0 µg/L | Over HA | 1 | B | |
| 72 | Mendon (T) | 350.0 µg/L | Over HA | 1 | B | |
| 73 | Ogden (T) | 350.0 µg/L | Over HA | 1 | B | |
| 74 | Parma (T) | 350.0 µg/L | Over HA | 1 | B | |
| 75 | Penfield (T) | 350.0 µg/L | Over HA | 1 | B | |
| 76 | Perinton (T) | 350.0 µg/L | Over HA | 1 | B | |
| 77 | Pittsford (T) | 350.0 µg/L | Over HA | 1 | B | |
| 78 | Pittsford (V) | 350.0 µg/L | Over HA | 1 | B | |
| 79 | Riga (T) | 350.0 µg/L | Over HA | 1 | B | |
| 80 | Rush (T) | 350.0 µg/L | Over HA | 2 | B | |
| 81 | Scottsville (V) | 350.0 µg/L | Over HA | 1 | B | |
| 82 | Spencerport (V) | 350.0 µg/L | Over HA | 1 | B | |
| 83 | Sweden (T) | 350.0 µg/L | Over HA | 1 | B | |
| 84 | Victor (T) | 350.0 µg/L | Over HA | 3 | B | |
| 85 | Webster (T) | 350.0 µg/L | Over HA | 1 | B | |
| 86 | Wheatland (T) | 350.0 µg/L | Over HA | 1 | B | |
| 87 | Batavia (T) | 350.0 µg/L | Over HA | 2 | B+ | |
| 88 | Victor (V) | 350.0 µg/L | Over HA | 3 | B | |
| 89 | Oakfield (T) | 350.0 µg/L | Over HA | 4 | B+ | |
| 90 | Oakfield (V) | 350.0 µg/L | Over HA | 4 | B+ | |
| 91 | Moreau (T) | 344.1 µg/L | Over HA | 4 | A- | |
| 92 | Binghamton (C) | 339.0 µg/L | Over HA | 5 | A- | |
| 93 | Patterson (T) | 325.3 µg/L | Over HA | 12 | C- | |
| 94 | Rensselaer (C) | 324.0 µg/L | Over HA | 6 | B+ | |
| 95 | Johnson City (V) | 308.0 µg/L | Over HA | 2 | A- | |
| 96 | Greenwood Lake (V) | 291.8 µg/L | Over HA | 9 | A- | |
| 97 | Alabama (T) | 270.0 µg/L | Over HA | 1 | A | |
| 98 | Bergen (T) | 270.0 µg/L | Over HA | 1 | A | |
| 99 | Bergen (V) | 270.0 µg/L | Over HA | 1 | A | |
| 100 | Bethany (T) | 270.0 µg/L | Over HA | 1 | A | |
| 101 | Byron (T) | 270.0 µg/L | Over HA | 1 | A | |
| 102 | Corfu (V) | 270.0 µg/L | Over HA | 1 | A | |
| 103 | Darien (T) | 270.0 µg/L | Over HA | 1 | A | |
| 104 | Le Roy (T) | 270.0 µg/L | Over HA | 1 | A | |
| 105 | Leroy (V) | 270.0 µg/L | Over HA | 1 | A | |
| 106 | Pavilion (T) | 270.0 µg/L | Over HA | 1 | A | |
| 107 | Pembroke (T) | 270.0 µg/L | Over HA | 1 | A | |
| 108 | Stafford (T) | 270.0 µg/L | Over HA | 1 | A- | |
| 109 | Fallsburg (T) | 270.0 µg/L | Over HA | 2 | F | |
| 110 | Tarrytown (V) | 266.0 µg/L | Over HA | 3 | B+ | |
| 111 | Guilderland (T) | 264.0 µg/L | Over HA | 18 | A- | |
| 112 | Monroe (T) | 250.0 µg/L | Over HA | 10 | F | |
| 113 | East Fishkill (T) | 250.0 µg/L | Over HA | 21 | F | |
| 114 | Cohoes (C) | 227.0 µg/L | Over HA | 5 | B+ | |
| 115 | Halfmoon (T) | 221.0 µg/L | Over HA | 3 | A | |
| 116 | Heuvelton (V) | 220.0 µg/L | Over HA | 0 | A | |
| 117 | Newburgh (C) | 217.0 µg/L | Over HA | 17 | A- | |
| 118 | Corning (C) | 210.0 µg/L | No | 2 | B- | |
| 119 | Mount Kisco (V) | 210.0 µg/L | No | 5 | A- | |
| 120 | New York (C) | 200.0 µg/L | No | 11 | A- | |
| 121 | Hempstead (V) | 200.0 µg/L | No | 1 | A- | |
| 122 | Poughkeepsie (C) | 200.0 µg/L | No | 2 | A | |
| 123 | Wallkill (T) | 200.0 µg/L | No | 23 | F | |
| 124 | Peekskill (C) | 190.0 µg/L | No | 15 | A- | |
| 125 | Wappinger (T) | 188.0 µg/L | No | 9 | D | |
| 126 | Lynbrook (V) | 180.0 µg/L | No | 3 | B | |
| 127 | Auburn (C) | 180.0 µg/L | No | 0 | A+ | |
| 128 | Garden City (V) | 180.0 µg/L | No | 5 | A- | |
| 129 | De Witt (T) | 180.0 µg/L | No | 6 | A- | |
| 130 | Oneonta (T) | 175.0 µg/L | No | 1 | C | |
| 131 | Oneonta (C) | 175.0 µg/L | No | 0 | A- | |
| 132 | Glen Cove (C) | 170.0 µg/L | No | 4 | B+ | |
| 133 | New Hyde Park (V) | 170.0 µg/L | No | 1 | A | |
| 134 | Glens Falls (C) | 170.0 µg/L | No | 17 | B+ | |
| 135 | Queensbury (T) | 160.0 µg/L | No | 2 | F | |
| 136 | Massena (V) | 153.0 µg/L | No | 2 | A- | |
| 137 | Yonkers (C) | 150.0 µg/L | No | 2 | B+ | |
| 138 | Freeport (V) | 150.0 µg/L | No | 2 | A+ | |
| 139 | Mineola (V) | 150.0 µg/L | No | 1 | A- | |
| 140 | Clay (T) | 150.0 µg/L | No | 2 | A+ | |
| 141 | Ogdensburg (C) | 150.0 µg/L | No | 1 | A- | |
| 142 | Jamestown (C) | 144.0 µg/L | No | 1 | A | |
| 143 | Brockport (V) | 141.0 µg/L | No | 0 | A- | |
| 144 | Deerfield (T) | 130.0 µg/L | No | 25 | B- | |
| 145 | Marcy (T) | 130.0 µg/L | No | 25 | B+ | |
| 146 | New Hartford (T) | 130.0 µg/L | No | 25 | B+ | |
| 147 | New Hartford (V) | 130.0 µg/L | No | 25 | B+ | |
| 148 | New York Mills (V) | 130.0 µg/L | No | 25 | B+ | |
| 149 | Oriskany (V) | 130.0 µg/L | No | 25 | B+ | |
| 150 | Utica (C) | 130.0 µg/L | No | 25 | B+ | |
| 151 | Whitesboro (V) | 130.0 µg/L | No | 25 | B+ | |
| 152 | Whitestown (T) | 130.0 µg/L | No | 25 | B+ | |
| 153 | Yorkville (V) | 130.0 µg/L | No | 25 | B+ | |
| 154 | White Plains (C) | 130.0 µg/L | No | 1 | A- | |
| 155 | Leray (T) | 130.0 µg/L | No | 4 | B+ | |
| 156 | Westmoreland (T) | 130.0 µg/L | No | 27 | B- | |
| 157 | Rockville Center (V) | 120.0 µg/L | No | 5 | A | |
| 158 | Scarsdale | 120.0 µg/L | No | 0 | A | |
| 159 | Horseheads (V) | 110.0 µg/L | No | 6 | D+ | |
| 160 | Mount Pleasant (T) | 103.0 µg/L | No | 36 | C | |
| 161 | Cortlandt (T) | 100.0 µg/L | No | 11 | B+ | |
| 162 | Woodbury (T) | 100.0 µg/L | No | 18 | C+ | |
| 163 | Vestal (T) | 95.0 µg/L | No | 2 | A- | |
| 164 | Mill Neck (V) | 95.0 µg/L | No | 2 | A | |
| 165 | Bethlehem (T) | 92.7 µg/L | No | 12 | A- | |
| 166 | Amsterdam (C) | 87.6 µg/L | No | 33 | B- | |
| 167 | Ramapo (T) | 86.6 µg/L | No | 19 | C+ | |
| 168 | Elmira (C) | 83.6 µg/L | No | 5 | B+ | |
| 169 | Elmira Heights (V) | 83.6 µg/L | No | 5 | B+ | |
| 170 | Elmira (T) | 83.6 µg/L | No | 5 | B+ | |
| 171 | Southport (T) | 83.6 µg/L | No | 5 | B+ | |
| 172 | Malta (T) | 82.0 µg/L | No | 3 | D | |
| 173 | Geneva (C) | 80.3 µg/L | No | 2 | A | |
| 174 | Ardsley (V) | 79.0 µg/L | No | 4 | B- | |
| 175 | Bronxville (V) | 79.0 µg/L | No | 4 | B- | |
| 176 | Dobbs Ferry (V) | 79.0 µg/L | No | 4 | B- | |
| 177 | Eastchester (T) | 79.0 µg/L | No | 4 | B- | |
| 178 | Hastings-On-Hudson (V) | 79.0 µg/L | No | 4 | B- | |
| 179 | New Rochelle (C) | 79.0 µg/L | No | 4 | B- | |
| 180 | Pelham Manor (V) | 79.0 µg/L | No | 4 | B- | |
| 181 | Pelham (V) | 79.0 µg/L | No | 4 | B- | |
| 182 | Tuckahoe (V) | 79.0 µg/L | No | 4 | B- | |
| 183 | Kingston (C) | 76.0 µg/L | No | 8 | A- | |
| 184 | Oneida (C) | 75.0 µg/L | No | 3 | A | |
| 185 | Oneida Castle (V) | 75.0 µg/L | No | 3 | A | |
| 186 | Albany (C) | 73.3 µg/L | No | 0 | A- | |
| 187 | Lyndonville (V) | 71.0 µg/L | No | 1 | A | |
| 188 | Roslyn (V) | 63.0 µg/L | No | 1 | A | |
| 189 | Westbury (V) | 55.0 µg/L | No | 2 | A- | |
| 190 | Glenville (T) | 53.0 µg/L | No | 0 | A | |
| 191 | Oswego (C) | 46.0 µg/L | No | 4 | A | |
| 192 | Massapequa Park (V) | 45.0 µg/L | No | 0 | A | |
| 193 | Lockport (T) | 45.0 µg/L | No | 0 | A+ | |
| 194 | Elma (T) | 35.0 µg/L | No | 0 | A+ | |
| 195 | Sea Cliff (V) | 33.0 µg/L | No | 0 | A+ | |
| 196 | Mamaroneck | 31.0 µg/L | No | 5 | B+ | |
| 197 | Mount Vernon (C) | 24.0 µg/L | No | 2 | A- | |
| 198 | Elmsford (V) | 22.3 µg/L | No | 0 | A- | |
| 199 | Fulton (C) | 22.0 µg/L | No | 2 | A | |
| 200 | Schenectady (C) | 21.2 µg/L | No | 1 | B+ |
FAQ
Frequently asked questions about chlorate in New York
Is chlorate in New York tap water dangerous?
Chlorate has no federal MCL. The EPA lifetime health advisory is 210 µg/L. 117 cities in New York 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 New York 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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All states
Chlorate in drinking water by state
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