Weakest County Drinking Water Report Cards

These county report cards highlight places with higher drinking-water violation exposure in EPA SDWIS data. A low score does not prove current tap water is unsafe; it identifies places where health-based violations and unresolved issues deserve closer reporting or public follow-up.

Read the scoring methodology or download the county report-card CSV.

ScoreGradeCountyStateSystemsPopulationHealth ViolationsPer 100KActive Health Systems
0FSandoval CountyNew Mexico62135,220897663.418
0FRio Arriba CountyNew Mexico6129,0928943073.019
0FSanta Fe CountyNew Mexico82146,462617421.323
0FTaos CountyNew Mexico9124,8335802335.619
0FSan Miguel CountyNew Mexico4423,9814251772.217
0FWindham CountyConnecticut25563,884382598.072
0FSan Juan CountyNew Mexico22103,721350337.46
0FTorrance CountyNew Mexico2610,4703062922.69
0FValencia CountyNew Mexico2851,356276537.48
0FMckinley CountyNew Mexico2834,524275796.59
0FTolland CountyConnecticut29359,720268448.858
0FEddy CountyNew Mexico2867,422249369.36
0FCibola CountyNew Mexico1820,1382391186.811
0FWade Hampton Census AreaAlaska137,6391922513.46
0FTulare CountyCalifornia12183,576191104.03
0FGrant CountyNew Mexico2726,969185686.07
0FGreenbrier CountyWest Virginia3529,747185621.914
0FMcdowell CountyWest Virginia2314,8811571055.015
0FRandolph CountyWest Virginia2925,710153595.112
0FPonce Municipio CountyPuerto Rico2135,111146415.810
0FWyoming CountyWest Virginia2015,488135871.611
0FMingo CountyWest Virginia1415,372124806.710
0FMercer CountyWest Virginia1331,615122385.94
0FLea CountyNew Mexico2366,976105156.86
0FRaleigh CountyWest Virginia1773,12399135.44
0FBarranquitas Municipio CountyPuerto Rico1121,18698462.68
0FVillalba Municipio CountyPuerto Rico1449,03193189.79
0FBureau CountyIllinois2225,47693365.07
0FYabucoa Municipio CountyPuerto Rico1427,61091329.69
0FJayuya Municipio CountyPuerto Rico1213,42688655.49
0FSanta Cruz CountyArizona3749,94687174.29
0FPocahontas CountyWest Virginia377,907871100.310
0FOrocovis Municipio CountyPuerto Rico1724,10680331.913
0FCurry CountyNew Mexico1653,91474137.34
0FSan Lorenzo Municipio CountyPuerto Rico1735,42372203.314
0FSocorro CountyNew Mexico1819,56071363.04
0FGuadalupe CountyNew Mexico126,387691080.38
0FCaguas Municipio CountyPuerto Rico2386,6096676.218
0FLuna CountyNew Mexico1419,51464328.03
0FSt. Lucie CountyFlorida44330,0236319.114
0FMartin CountyFlorida59161,2206339.114
0FWayne CountyWest Virginia1034,87861174.92
0FLogan CountyWest Virginia1034,33360174.87
0FMerced CountyCalifornia13199,6375829.13
0FPatillas Municipio CountyPuerto Rico1237,54358154.510
0FAguas Buenas Municipio CountyPuerto Rico1017,46857326.39
0FSummers CountyWest Virginia1722,82757249.77
0FHampshire CountyWest Virginia328,45256662.611
0FUtuado Municipio CountyPuerto Rico1625,73448186.513
0FPenuelas Municipio CountyPuerto Rico1122,06447213.06
0FChaves CountyNew Mexico1564,0594570.23
0FFayette CountyWest Virginia1237,59942111.77
0FAdjuntas Municipio CountyPuerto Rico1713,53742310.313
0FMarshall CountyWest Virginia1430,54641134.23
0FChristian CountyIllinois1126,25138144.83
0FCorozal Municipio CountyPuerto Rico1026,88833122.78
0FSiskiyou CountyCalifornia1019,78333166.86
0FWilliamson CountyIllinois1863,7863250.25
0FGrundy CountyIllinois1240,8062766.23
0FJackson CountyIllinois1341,0492560.93
0FMadison CountyFlorida1711,99722183.44
0FMonongalia CountyWest Virginia1282,8772226.53
0FKnox CountyIllinois1443,6671329.83
0FElko CountyNevada1029,0851137.82
0FWhiteside CountyIllinois1237,135924.25
0FJuana Diaz Municipio CountyPuerto Rico1121,739732.23
0FHolmes CountyFlorida226,447577.65
1FBethel Census AreaAlaska5718,2537083878.811
1FNew London CountyConnecticut396209,068432206.678
2FMora CountyNew Mexico214,3411924422.94
3FBernalillo CountyNew Mexico80643,28359692.615
3FMarion CountyWest Virginia2757,736111192.35
3FGraham CountyArizona1629,7392480.73
4FOtero CountyNew Mexico5571,033301423.710
4FStanislaus CountyCalifornia22465,09811825.44
5FColfax CountyNew Mexico3421,8287943637.56
5FWoodford CountyIllinois1725,20439154.73
5FBerkeley CountyWest Virginia2397,3282121.64
5FIndian River CountyFlorida17168,214169.53
5FPendleton CountyWest Virginia173,46314404.33
5FVermilion CountyIllinois1754,184916.63
7FYukon-Koyukuk Census AreaAlaska366,1875148307.76
7FBlaine CountyMontana122,672953555.42
7FRandolph CountyIllinois1224,24342173.22
7FRock Island CountyIllinois18131,7952922.03
9FYuma CountyArizona51217,7201,134520.98
9FLincoln CountyWyoming3917,547165940.36
9FHartford CountyConnecticut219836,03216319.534
9FCatron CountyNew Mexico132,139954441.32
9FMacon CountyIllinois13102,9903029.12
9FMontgomery CountyIllinois1313,78318130.62
10FMiddlesex CountyConnecticut27697,390232238.241
10FMacoupin CountyIllinois2032,20356173.93
11FLasalle CountyIllinois2182,9674453.03
11FIroquois CountyIllinois2119,35338196.43
11FVermillion CountyIndiana1414,15928197.82
11FMinnehaha CountySouth Dakota14241,302197.92
11FHenry CountyIllinois1434,5511028.92
13FLincoln CountyNew Mexico5236,231138380.97
13FBristol Bay BoroughAlaska305,169671296.24