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National Drinking Water Database


National Drinking Water Database - Chemical Contaminants

The Most Polluted Communities

11,173 water utilities reported detecting Arsenic (total) in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by population

RankSystem Population Served Positive test results of total reported tests Average Level
(Range)
1Metropolitan Water District of Southern California
Los Angeles, CA
17,000,00015 of 181.38 ppb
(0 to 3.4 ppb)
2Los Angeles Department of Water and Power
Los Angeles, CA
3,828,70056 of 802.57 ppb
(0 to 8.1 ppb)
3Chicago Department of Water Management
Chicago, IL
2,896,0161 of 60.17 ppb
(0 to 1 ppb)
4City of Houston Public Works
Houston, TX
2,700,00019 of 232.89 ppb
(0 to 6.76 ppb)
5Miami-Dade Water & Sewer Department
Miami, FL
2,100,0001 of 40.17 ppb
(0 to 0.67 ppb)
6Washington Suburban Sanitary Commission
Silver Spring, MD
1,800,00017 of 510.14 ppb
(0 to 1 ppb)
7Philadelphia Water Department
Philadelphia, PA
1,600,0002 of 100.3 ppb
(0 to 2 ppb)
8Cleveland Division of Water
Cleveland, OH
1,500,0001 of 100.26 ppb
(0 to 2.55 ppb)
9City of Phoenix Water Services Department
Phoenix, AZ
1,200,00034 of 1381.62 ppb
(0 to 13.1 ppb)
10Las Vegas Valley Water District
Las Vegas, NV
1,181,2638 of 171.13 ppb
(0 to 4 ppb)
11Suffolk County Water Authority
Bay Shore, NY
1,009,2641 of 10.06 ppb
(0.06 ppb)
12San Jose Water Company
San Jose, CA
979,00039 of 930.25 ppb
(0 to 2.33 ppb)
13Indianapolis Water
Indianapolis, IN
805,4311 of 210.05 ppb
(0 to 1.1 ppb)
14San Francisco Public Utilities Commission
San Francisco, CA
800,0001 of 40.64 ppb
(0 to 2.55 ppb)
15JEA
Jacksonville, FL
800,0005 of 240.23 ppb
(0 to 3.4 ppb)
16United Water New Jersey
Haworth, NJ
773,4581 of 70.14 ppb
(0 to 1 ppb)
17Tucson Water
Tucson, AZ
675,00035 of 523.44 ppb
(0 to 16 ppb)
18Pennsylvania American Water Company- Pittsburgh
Mcmurray, PA
660,0002 of 30.67 ppb
(0 to 1 ppb)
19New Jersey American - Elizabethtown
Plainfield, NJ
609,38712 of 171.55 ppb
(0 to 7 ppb)
20Oklahoma City Water Utilities Trust
Oklahoma City, OK
598,0001 of 12.8 ppb
(2.8 ppb)