The Power of Information

National Drinking Water Database


National Drinking Water Database - City Water Ratings

Big City Water Ratings


EWG rated big city (population over 250,000) water utilities based on three factors: the total number of chemicals detected since 2004; the percentage of chemicals found of those tested; and the highest average level for an individual pollutant, relative to legal limits or national average amounts, including for the most common pollutants (disinfection byproducts, nitrate and arsenic). [read more on rating methodology]


 RANK  WATER UTILITY  CHEMICALS FOUND  TOP CONCERN ***  NATIONAL POLLUTANTS
1Arlington, TX
(Arlington Water Utilities serves 290,000 people)
7 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 6.7 ppb
HAAs: 2.3 ppb
nitrate: 0.4 ppm
arsenic: 0.0 ppb
2Providence, RI
(Providence Water serves 295,700 people)
4 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 22.5 ppb
HAAs: 16.4 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
3Fort Worth, TX
(Fort Worth Water Department serves 501,954 people)
7 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 22.6 ppb
HAAs: 11.9 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
4Charleston, SC
(Charleston Water System serves 327,620 people)
5 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 23.7 ppb
HAAs: 21.3 ppb
nitrate: 0.4 ppm
arsenic: 0.0 ppb
5Boston, MA
(Massachusetts Water Resources Authority serves 2,000,000 people)
14 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 3.7 ppb
HAAs: 3.7 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
6Honolulu, HI
(Board of Water Supply (Honolulu/Windward/Pearl Harbor) serves 661,004 people)
8 *DieldrinDieldrin is a banned insecticide that is persistent and bioaccumulative, and was historically used on corn, cotton and citrus; it also forms in the environment as a breakdown product of the pesticide aldrin.THMs: 0.8 ppb
HAAs:<0.1 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
7Austin, TX
(Austin Water Utility serves 669,693 people)
5 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 30.6 ppb
HAAs: 14.8 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
8Fairfax County, VA
(Fairfax Water serves 823,216 people)
8 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform. **THMs: 23.0 ppb
HAAs: 16.0 ppb
nitrate: 1.0 ppm
arsenic: 0.0 ppb
9St. Louis, MO
(City of St. Louis Water Division serves 370,000 people)
7Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 15.4 ppb
HAAs: 19.2 ppb
nitrate: 2.7 ppm
arsenic: 0.0 ppb
10Minneapolis, MN
(City of Minneapolis Water Department serves 382,618 people)
6 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 29.6 ppb
HAAs: 27.3 ppb
nitrate: 0.4 ppm
arsenic: 0.0 ppb
11Richmond, VA
(Henrico County Public Utilities serves 289,000 people)
9 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 15.0 ppb
HAAs: 21.5 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
12Dallas, TX
(Dallas Water Utilities serves 1,188,580 people)
9 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 32.1 ppb
HAAs: 24.0 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
13New York, NY
(New York City Department of Environmental Protection- Jamaica serves 518,000 people)
4 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 30.8 ppb
HAAs: 32.0 ppb
nitrate: n/a
arsenic: 0.0 ppb
14Oklahoma City, OK
(Oklahoma City Water Utilities Trust serves 598,000 people)
5Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 40.0 ppb
HAAs: 23.5 ppb
nitrate: 0.1 ppm
arsenic: 2.8 ppb
15Buffalo, NY
(Buffalo Water Authority serves 345,974 people)
9 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 32.3 ppb
HAAs: 18.9 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
16Cinncinnati, OH
(Greater Cincinnati Water Works serves 775,000 people)
8 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 33.0 ppb
HAAs: 8.1 ppb
nitrate: 1.4 ppm
arsenic: 0.0 ppb
17St. Paul, MN
(Saint Paul Regional Water Services serves 414,735 people)
11 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 31.1 ppb
HAAs: 18.2 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
18Sacramento, CA
(City of Sacramento Department of Utilities serves 407,018 people)
14 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 1.4 ppb
HAAs: 17.7 ppb
nitrate: 1.3 ppm
arsenic: 2.9 ppb
19Milwaukee, WI
(Milwaukee Water Works serves 647,290 people)
14 *BromateBromate is a carcinogenic disinfection byproduct of ozonation formed when source waters contain high levels of natural bromide; it can also form following water treatment with chlorine dioxide or hypochlorite.THMs: 5.4 ppb
HAAs: 1.1 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
20Odessa, FL
(St. Petersburg Water Resources Department serves 300,075 people)
13 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 16.4 ppb
HAAs: 14.0 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
21Bridgeport, CT
(Aquarion Water Company serves 341,421 people)
6Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 40.0 ppb
HAAs: 31.0 ppb
nitrate: 1.2 ppm
arsenic: 0.0 ppb
22Louisville, KY
(Louisville Water Company serves 836,926 people)
12Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 22.8 ppb
HAAs: 13.9 ppb
nitrate: 1.0 ppm
arsenic: 0.0 ppb
23Hartfort, CT
(Metropolitan District Commission serves 388,700 people)
9Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform. **THMs: 33.2 ppb
HAAs: 23.5 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
24Springfield, MA
(Springfield Water & Sewer Commission serves 250,000 people)
4 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 50.8 ppb
HAAs: 38.4 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
25Seattle, WA
(Seattle Public Utilities serves 629,000 people)
9 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 31.5 ppb
HAAs: 25.2 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
26Greensboro, NC
(City of Greensboro Department of Water Resources serves 250,000 people)
5 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 42.6 ppb
HAAs: 36.6 ppb
nitrate: 0.4 ppm
arsenic: 0.0 ppb
27Newport News, VA
(Newport News Water Works serves 406,000 people)
10 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 24.6 ppb
HAAs: 23.5 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
28Winston-Salem, NC
(Winston-Salem/Forsyth County Utility Commission serves 286,028 people)
10 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 29.4 ppb
HAAs: 27.9 ppb
nitrate: 1.9 ppm
arsenic: 0.0 ppb
29San Antonio, TX
(San Antonio Water System serves 1,219,113 people)
20 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 15.4 ppb
HAAs: 11.6 ppb
nitrate: 1.7 ppm
arsenic: 0.0 ppb
30Kent, OH
(Akron Public Utilities Bureau serves 320,000 people)
6 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 45.8 ppb
HAAs: 34.2 ppb
nitrate: 0.6 ppm
arsenic: 0.0 ppb
31Birmingham, AL
(Birmingham Water Works & Sewer Board serves 585,000 people)
10 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 30.5 ppb
HAAs: 23.2 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
32Pittsburgh, PA
(Pennsylvania American Water Company- Pittsburgh serves 660,000 people)
4Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 54.0 ppb
HAAs: 13.1 ppb
nitrate: 0.7 ppm
arsenic: 0.0 ppb
33San Francisco, CA
(San Francisco Public Utilities Commission serves 800,000 people)
14 *NitrateNitrate enters drinking water sources from fertilizer runoff, leaching septic tanks, and erosion of natural deposits; it is also emitted by chemical, petrochemical and metal-finishing industries.THMs: 8.6 ppb
HAAs: 24.9 ppb
nitrate: 4.2 ppm
arsenic: 0.0 ppb
34Chicago, IL
(Chicago Department of Water Management serves 2,896,016 people)
15 *Combined Radium (-226 & -228)Radium is a radioactive element usually found around uranium deposits.THMs: 16.1 ppb
HAAs: 8.2 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
35Toledo, OH
(City of Toledo Division of Water serves 380,000 people)
10 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 35.7 ppb
HAAs: 11.9 ppb
nitrate: 1.2 ppm
arsenic: 0.0 ppb
36Oakland, CA
(East Bay Municipal Utility District serves 1,300,000 people)
14Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform. **THMs: 28.0 ppb
HAAs: 16.0 ppb
nitrate: 0.0 ppm
arsenic: 0.1 ppb
37New Haven, CT
(South Central Connecticut Regional Water Authority serves 389,300 people)
10Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform. **THMs: 37.0 ppb
HAAs: 26.0 ppb
nitrate: 1.4 ppm
arsenic: 0.0 ppb
38Manatee County, FL
(Manatee County Utilities Department serves 253,263 people)
17 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 22.8 ppb
HAAs: 14.1 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
39Monroe County, NY
(Monroe County Water Authority- Shoremont Water Treatment Plant serves 490,000 people)
6Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 53.8 ppb
HAAs: 6.0 ppb
nitrate: 0.4 ppm
arsenic: 0.0 ppb
40Long Beach, CA
(Long Beach Water Department serves 452,905 people)
15 *Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides. **THMs: 2.6 ppb
HAAs: 10.5 ppb
nitrate: 0.0 ppm
arsenic: 4.2 ppb
41New York, NY
(New York City Department of Environmental Protection- Catskill/Delaware serves 6,552,718 people)
5 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 37.3 ppb
HAAs: 42.6 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
42Layton, UT
(Weber Basin Water Conservancy District serves 298,000 people)
13 *Thallium (total)Thallium is a highly toxic metal that contaminates the environment due to leaching from ore-processing sites, discharge from electronics, glass, and drug factories and historical use as rodenticideTHMs: 18.2 ppb
HAAs: 15.6 ppb
nitrate: 0.8 ppm
arsenic: 0.0 ppb
43Fort Wayne, IN
(Fort Wayne City Utilities- Three Rivers Filtration Plant serves 250,000 people)
16 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 22.8 ppb
HAAs: 14.4 ppb
nitrate: 1.9 ppm
arsenic: 0.0 ppb
44Corpus Christi, TX
(City of Corpus Christi Water Department serves 270,000 people)
13 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 38.0 ppb
HAAs: 26.5 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
45Tacoma, WA
(City of Tacoma Water Division serves 305,000 people)
19 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 6.5 ppb
HAAs: 20.6 ppb
nitrate: 2.5 ppm
arsenic: 0.6 ppb
46Miami, FL
(Miami-Dade Water & Sewer Department serves 2,100,000 people)
14 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 18.7 ppb
HAAs: 22.4 ppb
nitrate: 0.8 ppm
arsenic: 0.0 ppb
47Palm Beach County, CA
(Palm Beach County Water Utilities Department serves 416,303 people)
16 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 24.7 ppb
HAAs: 17.8 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
48Bryn Mawr, PA
(Aqua Pennsylvania Inc. (Aqua) serves 820,000 people)
14Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 31.7 ppb
HAAs: 22.3 ppb
nitrate: 3.8 ppm
arsenic: 0.0 ppb
49Erie County, NY
(Erie County Water Authority serves 402,180 people)
8 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 53.7 ppb
HAAs: 21.7 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
50Plano, TX
(City of Plano Utility Operations Department serves 291,144 people)
6 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 58.3 ppb
HAAs: 22.0 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
51Albuquerque, NM
(Albuquerque Bernalillo County Water Authority serves 453,000 people)
9 *Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides. **THMs: 6.2 ppb
HAAs: 2.3 ppb
nitrate: 0.4 ppm
arsenic: 7.0 ppb
52St. Louis County, MO
(Missouri American Water- St. Louis County/ St. Charles County serves 1,049,600 people)
14 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 12.0 ppb
HAAs: 24.8 ppb
nitrate: 0.9 ppm
arsenic: 0.6 ppb
53Phoenix, AZ
(City of Phoenix Water Services Department serves 1,200,000 people)
13Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 38.5 ppb
HAAs: 16.3 ppb
nitrate: 1.7 ppm
arsenic: 0.0 ppb
54Stockton, CA
(Stockton East Water District serves 250,000 people)
15 *Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides.THMs: 27.1 ppb
HAAs: 8.9 ppb
nitrate: 0.6 ppm
arsenic: 0.0 ppb
55New York, NY
(New York City Department of Environmental Protection- Croton serves 1,000,000 people)
5 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 46.5 ppb
HAAs: 47.9 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
56Mobile, AL
(Mobile Area Water & Sewer System serves 274,995 people)
13 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 72.2 ppb
HAAs: 26.2 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
57Pinellas County, FL
(Pinellas County Utilities serves 426,877 people)
16 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 30.1 ppb
HAAs: 16.1 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
58Los Angeles Suburbs, CA
(Metropolitan Water District of Southern California serves 17,000,000 people)
22 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 30.8 ppb
HAAs: 14.0 ppb
nitrate: 0.2 ppm
arsenic: 2.3 ppb
59Portland, OR
(Portland Water Bureau serves 539,200 people)
15Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 20.2 ppb
HAAs: 26.1 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
60Philadelphia, PA
(Philadelphia Water Department serves 1,600,000 people)
12Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 44.6 ppb
HAAs: 31.4 ppb
nitrate: 2.7 ppm
arsenic: 0.0 ppb
61Santa Ana, CA
(City of Santa Ana Public Works serves 293,700 people)
20NitrateNitrate enters drinking water sources from fertilizer runoff, leaching septic tanks, and erosion of natural deposits; it is also emitted by chemical, petrochemical and metal-finishing industries.THMs: 15.0 ppb
HAAs: 4.2 ppb
nitrate: 4.6 ppm
arsenic: 1.1 ppb
62Totowa Borough, NJ
(Passaic Valley Water Commission serves 314,900 people)
19 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 38.1 ppb
HAAs: 26.5 ppb
nitrate: 1.7 ppm
arsenic: 0.0 ppb
63Mahwah, NJ
(United Water New Jersey serves 773,458 people)
19 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 34.6 ppb
HAAs: 26.9 ppb
nitrate: 1.5 ppm
arsenic: 0.0 ppb
64Norfolk, VA
(Norfolk Department of Utilities serves 755,617 people)
11 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 49.5 ppb
HAAs: 30.0 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
65Hillsborough County, FL
(Hillsborough County Water Resource Services- South Hillsborough serves 303,000 people)
18 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 27.7 ppb
HAAs: 13.4 ppb
nitrate: 0.6 ppm
arsenic: 0.0 ppb
66Tucson, AZ
(Tucson Water serves 675,000 people)
19 *Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides.THMs: 5.7 ppb
HAAs: 0.2 ppb
nitrate: 1.9 ppm
arsenic: 0.0 ppb
67Lexington, KY
(Kentucky-American Water serves 354,473 people)
12Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 48.9 ppb
HAAs: 26.8 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
68Tampa, FL
(Tampa Water Department serves 550,000 people)
19 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 26.4 ppb
HAAs: 16.2 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
69Baltimore, MD
(Baltimore City Department of Public Works serves 1,600,000 people)
12 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 44.5 ppb
HAAs: 42.1 ppb
nitrate: 1.8 ppm
arsenic: 0.0 ppb
70Alameda County, CA
(Alameda County Water District serves 271,000 people)
27 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 14.2 ppb
HAAs: 20.9 ppb
nitrate: 1.3 ppm
arsenic: 0.0 ppb
71Tulsa, OK
(City of Tulsa Water Supply System serves 471,000 people)
13 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 48.4 ppb
HAAs: 18.9 ppb
nitrate: 0.5 ppm
arsenic: 0.0 ppb
72Cleveland OH
(Cleveland Division of Water serves 1,500,000 people)
19 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 22.5 ppb
HAAs: 22.3 ppb
nitrate: 0.4 ppm
arsenic: 0.0 ppb
73Pittsburgh City, PA
(Pittsburgh Water & Sewer Authority serves 250,000 people)
11Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 57.5 ppb
HAAs: 15.4 ppb
nitrate: 1.2 ppm
arsenic: 7.0 ppb
74Raleigh, NC
(City of Raleigh Public Utilities Department serves 409,542 people)
19 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 42.2 ppb
HAAs: 31.4 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
75Columbus, OH
(City of Columbus Department of Public Utilities serves 897,213 people)
8 *PhosphorusPhosphorus is a component of fertilizer and manure, and a common pollutant in municipal wastewater discharges.THMs: 32.5 ppb
HAAs: 27.3 ppb
nitrate: 1.6 ppm
arsenic: 0.0 ppb
76Mesa, AZ
(City of Mesa Utilities Department serves 350,000 people)
21 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 33.3 ppb
HAAs: 13.7 ppb
nitrate: 1.3 ppm
arsenic: 0.0 ppb
77Charlotte, NC
(Charlotte-Mecklenburg Utilities serves 761,830 people)
20 *Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 43.1 ppb
HAAs: 17.1 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
78Little Rock, AR
(Central Arkansas Water serves 323,212 people)
13 *Dibenz[a,h]anthraceneDibenz[a,h]anthracene a polycyclic aromatic hydrocarbon (PAH) released from the incomplete combustion of fossil fuels.THMs: 49.8 ppb
HAAs: 29.7 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
79Anaheim, CA
(Anaheim Public Utilities serves 345,556 people)
28 *Alpha particle activityAlpha particles are a form of radiation released from mining waste pollutants and natural sources.THMs: 3.2 ppb
HAAs: 18.0 ppb
nitrate: 3.1 ppm
arsenic: 1.7 ppb
80Salt Lake City, UT
(Salt Lake City Department of Public Utilities serves 312,000 people)
24 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 12.2 ppb
HAAs: 26.7 ppb
nitrate: 1.5 ppm
arsenic: 0.0 ppb
81Orlando, FL
(Orlando Utilities Commission serves 414,500 people)
17Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 50.4 ppb
HAAs: 20.1 ppb
nitrate: 0.0 ppm
arsenic: 0.0 ppb
82Montgomery & Prince George's Counties, MD
(Washington Suburban Sanitary Commission serves 1,800,000 people)
22 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 31.8 ppb
HAAs: 34.6 ppb
nitrate: 1.5 ppm
arsenic: 0.0 ppb
83Los Angeles, CA
(Los Angeles Department of Water and Power serves 3,828,700 people)
25 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid. **THMs: 34.4 ppb
HAAs: 29.0 ppb
nitrate: 1.5 ppm
arsenic: 2.6 ppb
84San Jose, CA
(San Jose Water Company serves 979,000 people)
30 *NitrateNitrate enters drinking water sources from fertilizer runoff, leaching septic tanks, and erosion of natural deposits; it is also emitted by chemical, petrochemical and metal-finishing industries.THMs: 1.8 ppb
HAAs: 10.0 ppb
nitrate: 4.7 ppm
arsenic: 0.4 ppb
85Haworth Boro, NJ
(United Water- New Jersey serves 253,045 people)
32 *DieldrinDieldrin is a banned insecticide that is persistent and bioaccumulative, and was historically used on corn, cotton and citrus; it also forms in the environment as a breakdown product of the pesticide aldrin.THMs: 13.3 ppb
HAAs: 3.4 ppb
nitrate: 0.6 ppm
arsenic: 0.0 ppb
86Cocoa, FL
(City of Cocoa- Claude H. Dyal Water Treatment Plant serves 260,887 people)
19Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 49.8 ppb
HAAs: 25.4 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
87West Milford
(City of Newark Department of Water serves 273,000 people)
18 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 48.4 ppb
HAAs: 51.4 ppb
nitrate: 0.3 ppm
arsenic: 0.0 ppb
88Chino Hills, CA
(Chino Hills Water & Sewer serves 520,000 people)
18 *NitrateNitrate enters drinking water sources from fertilizer runoff, leaching septic tanks, and erosion of natural deposits; it is also emitted by chemical, petrochemical and metal-finishing industries.THMs: 0.4 ppb
HAAs: 7.9 ppb
nitrate: 8.4 ppm
arsenic: 7.5 ppb
89Fresno, CA
(City of Fresno Water Division serves 390,350 people)
30 *NitrateNitrate enters drinking water sources from fertilizer runoff, leaching septic tanks, and erosion of natural deposits; it is also emitted by chemical, petrochemical and metal-finishing industries.THMs: 0.1 ppb
HAAs: 1.7 ppb
nitrate: 5.0 ppm
arsenic: 2.6 ppb
90Indianapolis, IN
(Indianapolis Water serves 805,431 people)
23 *Total haloacetic acids (HAAs)Total haloacetic acids refers to the sum of the concentrations of five related disinfection byproducts in a water sample: dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, monobromoacetic acid and dibromoacetic acid.THMs: 33.6 ppb
HAAs: 36.6 ppb
nitrate: 1.2 ppm
arsenic: 0.0 ppb
91Jacksonville, FL
(JEA serves 800,000 people)
23Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform.THMs: 48.0 ppb
HAAs: 13.3 ppb
nitrate: 0.1 ppm
arsenic: 0.0 ppb
92San Diego, CA
(San Diego Water Department serves 1,281,400 people)
24 *Gross beta particle activity (pCi/L)Beta particles are a form of radiation frequently associated with nuclear testing and radioactive mineral deposits.THMs: 41.0 ppb
HAAs: 17.8 ppb
nitrate: 0.5 ppm
arsenic: 0.0 ppb
93North Las Vegas, NV
(City of North Las Vegas Utilities Department serves 282,600 people)
29Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform. **THMs: 50.0 ppb
HAAs: 18.0 ppb
nitrate: 0.8 ppm
arsenic: 2.1 ppb
94Omaha, NE
(Metropolitan Utilities District serves 506,420 people)
32 *Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides. **THMs: 16.6 ppb
HAAs: 17.0 ppb
nitrate: 1.4 ppm
arsenic: 5.6 ppb
95Houston, TX
(City of Houston Public Works serves 2,700,000 people)
37 *Alpha particle activityAlpha particles are a form of radiation released from mining waste pollutants and natural sources.THMs: 20.1 ppb
HAAs: 22.2 ppb
nitrate: 0.2 ppm
arsenic: 0.0 ppb
96Reno, NV
(Truckee Meadows Water Authority serves 315,200 people)
23Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides. **THMs: 39.6 ppb
HAAs: 20.4 ppb
nitrate: 0.1 ppm
arsenic: 6.8 ppb
97Riverside County, CA
(Eastern Municipal Water District serves 480,000 people)
32 *PerchloratePerchlorate is a synthetic oxygen additive in solid fuel propellant for rockets, missiles, and fireworks, and is primarily used by the military and the space industry; it may occur naturally in certain imported agricultural fertilizers.THMs: 8.8 ppb
HAAs: 14.5 ppb
nitrate: 3.5 ppm
arsenic: 0.0 ppb
98Las Vegas, NV
(Las Vegas Valley Water District serves 1,181,263 people)
33Total trihalomethanes (TTHMs)Total trihalomethanes constitute the sum of four disinfection byproducts: chloroform, bromodichloromethane, dibromochloromethane, and bromoform. **THMs: 62.0 ppb
HAAs: 27.0 ppb
nitrate: 0.9 ppm
arsenic: 2.1 ppb
99Riverside, CA
(City of Riverside Public Utilities serves 280,832 people)
36 *PerchloratePerchlorate is a synthetic oxygen additive in solid fuel propellant for rockets, missiles, and fireworks, and is primarily used by the military and the space industry; it may occur naturally in certain imported agricultural fertilizers.THMs: 0.9 ppb
HAAs: 0.9 ppb
nitrate: 6.0 ppm
arsenic: 0.0 ppb
100Pensacola, FL
(Emerald Coast Water Utility serves 307,076 people)
39 *MTBEMTBE (methyl tert-butyl ether) is a fuel additive that had been used as an octane enhancer in unleaded gasoline; it contaminates groundwater due to spillage or leakage at gas stations, and has been banned or scheduled for phaseout in most states.THMs: 0.2 ppb
HAAs: 0.6 ppb
nitrate: 1.4 ppm
arsenic: 0.0 ppb

The following large utilities had insufficient data available and could not be included in the rankings:

 

* The count of chemicals found treats THMs and HAAs as one chemical each, to account for differences in the various state databases that underlie this analysis. This count may differ from that shown on a utility's water quality report within this website, where individual THM and HAA chemicals are included in the total.

** Recent data was not provided by the state. Value shown is taken from the water utility's 2008 Consumer Confidence Report (CCR).

***"Top concern" lists the chemical with the highest average level relative to the legal limit for regulated compounds, or to the national average concentration for unregulated compounds (among those utilities detecting the chemical).