Spatial Anomaly Clusters — Neighboring ZIPs With Shared Contamination

Analysis of 992 geographic clusters where 3 or more neighboring ZIP codes share the same water contamination issue

Last updated: 2026-06-03

When multiple neighboring ZIP codes share the same water quality problem, it often points to a common cause: shared water infrastructure, regional groundwater contamination, or widespread industrial pollution. This page maps 992 spatial clusters where 3+ ZIP codes within a 15-mile radius share the same issue.

Summary

Issue Type	Clusters	ZIP Codes	Population Affected
Lead Contamination	45	340	16,014,758
PFAS Contamination	10	299	13,354,210
Health Violations	937	9,194	399,521,111

Largest Clusters

#1: New York, NY

PFAS Contamination — 213 ZIP codes within 18.1 miles

Population affected: 8,691,715
Severity score: 18,513,352,950
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 10001, 10002, 10003, 10004, 10005, 10006, 10007, 10008, 10009, 10010, 10011, 10012, 10013, 10014, 10015, 10016, 10017, 10018, 10019, 10020 ... and 193 more

#2: Kearny, NJ

Health Violations — 86 ZIP codes within 12.1 miles

Population affected: 9,643,236
Severity score: 8,293,182,960
Shared water system detected — multiple ZIPs served by the same utility
Cross-state cluster: NJ, NY
ZIP codes: 07003, 07009, 07011, 07012, 07013, 07014, 07015, 07032, 07044, 07050, 07051, 07099, 07101, 07102, 07103, 07104, 07105, 07106, 07107, 07108 ... and 66 more

#3: Washington, DC

Health Violations — 281 ZIP codes within 16.7 miles

Population affected: 4,517,325
Severity score: 7,616,209,950
Shared water system detected — multiple ZIPs served by the same utility
Cross-state cluster: DC, MD
ZIP codes: 20001, 20002, 20003, 20004, 20005, 20006, 20007, 20008, 20009, 20010, 20011, 20012, 20013, 20015, 20016, 20017, 20018, 20019, 20020, 20022 ... and 261 more

#4: San Antonio, TX

Health Violations — 85 ZIP codes within 21.9 miles

Population affected: 8,605,065
Severity score: 7,314,305,250
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 78015, 78023, 78201, 78202, 78203, 78204, 78205, 78206, 78207, 78208, 78209, 78210, 78211, 78212, 78213, 78214, 78215, 78216, 78217, 78218 ... and 65 more

#5: Los Angeles, CA

Health Violations — 125 ZIP codes within 16.8 miles

Population affected: 9,700,653
Severity score: 6,062,908,125
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 90001, 90002, 90003, 90004, 90005, 90006, 90007, 90008, 90009, 90010, 90011, 90012, 90013, 90014, 90015, 90016, 90017, 90018, 90019, 90020 ... and 105 more

#6: San Francisco, CA

Health Violations — 96 ZIP codes within 23.8 miles

Population affected: 5,096,153
Severity score: 4,892,306,880
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 94030, 94065, 94101, 94102, 94103, 94104, 94105, 94107, 94108, 94109, 94110, 94111, 94112, 94114, 94115, 94117, 94118, 94119, 94120, 94123 ... and 76 more

#7: Phoenix, AZ

Health Violations — 109 ZIP codes within 17.2 miles

Population affected: 3,521,754
Severity score: 3,838,711,860
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 85001, 85002, 85003, 85004, 85005, 85006, 85007, 85008, 85009, 85010, 85011, 85012, 85013, 85014, 85015, 85016, 85017, 85018, 85019, 85020 ... and 89 more

#8: Orlando, FL

Health Violations — 74 ZIP codes within 16.1 miles

Population affected: 4,483,640
Severity score: 2,322,525,520
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 32701, 32703, 32714, 32715, 32716, 32750, 32752, 32762, 32765, 32766, 32773, 32779, 32789, 32790, 32791, 32792, 32793, 32801, 32802, 32803 ... and 54 more

#9: Milwaukee, WI

Health Violations — 59 ZIP codes within 18.2 miles

Population affected: 3,292,347
Severity score: 1,942,484,730
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 53005, 53008, 53018, 53022, 53045, 53064, 53072, 53089, 53097, 53122, 53130, 53150, 53183, 53186, 53187, 53188, 53189, 53201, 53202, 53203 ... and 39 more

#10: Tucson, AZ

Health Violations — 52 ZIP codes within 17.3 miles

Population affected: 3,383,105
Severity score: 1,759,214,600
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 85654, 85701, 85702, 85703, 85704, 85705, 85706, 85707, 85708, 85709, 85710, 85711, 85712, 85713, 85714, 85715, 85716, 85717, 85718, 85719 ... and 32 more

#11: Pittsburgh, PA

Health Violations — 87 ZIP codes within 16.1 miles

Population affected: 4,024,166
Severity score: 1,750,512,210
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 15003, 15030, 15049, 15056, 15071, 15084, 15104, 15110, 15143, 15146, 15201, 15202, 15203, 15204, 15205, 15206, 15207, 15208, 15209, 15210 ... and 67 more

#12: Houston, TX

Health Violations — 181 ZIP codes within 16 miles

Population affected: 9,613,232
Severity score: 1,739,994,992
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 77001, 77002, 77003, 77004, 77005, 77006, 77007, 77008, 77009, 77010, 77011, 77012, 77013, 77014, 77015, 77016, 77017, 77018, 77019, 77020 ... and 161 more

#13: Austin, TX

Health Violations — 84 ZIP codes within 14.9 miles

Population affected: 6,224,130
Severity score: 1,568,480,760
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 73301, 73344, 78617, 78652, 78660, 78691, 78701, 78702, 78703, 78704, 78705, 78708, 78709, 78710, 78711, 78712, 78713, 78714, 78715, 78716 ... and 64 more

#14: San Diego, CA

Health Violations — 83 ZIP codes within 15.6 miles

Population affected: 4,709,360
Severity score: 1,563,507,520
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 91932, 91933, 92071, 92072, 92101, 92102, 92103, 92104, 92105, 92106, 92107, 92108, 92109, 92110, 92111, 92112, 92113, 92114, 92115, 92116 ... and 63 more

#15: Raleigh, NC

Health Violations — 69 ZIP codes within 18.8 miles

Population affected: 2,253,212
Severity score: 1,554,716,280
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 27502, 27511, 27512, 27513, 27517, 27518, 27519, 27523, 27539, 27587, 27601, 27602, 27603, 27604, 27605, 27606, 27607, 27608, 27609, 27610 ... and 49 more

#16: Sacramento, CA

Health Violations — 111 ZIP codes within 19.8 miles

Population affected: 2,741,977
Severity score: 1,521,797,235
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 94203, 94204, 94205, 94206, 94207, 94208, 94209, 94211, 94229, 94230, 94232, 94234, 94235, 94236, 94237, 94239, 94240, 94244, 94245, 94246 ... and 91 more

#17: Fort Worth, TX

Health Violations — 78 ZIP codes within 16.7 miles

Population affected: 5,549,303
Severity score: 1,298,536,902
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 75050, 75051, 75052, 75053, 75054, 76001, 76002, 76003, 76004, 76005, 76006, 76007, 76010, 76011, 76012, 76013, 76014, 76015, 76016, 76017 ... and 58 more

#18: Tulsa, OK

Health Violations — 63 ZIP codes within 13.2 miles

Population affected: 1,879,236
Severity score: 1,183,918,680
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 74008, 74011, 74012, 74013, 74014, 74037, 74050, 74055, 74063, 74066, 74067, 74101, 74102, 74103, 74104, 74105, 74106, 74107, 74108, 74110 ... and 43 more

#19: Charlotte, NC

Health Violations — 81 ZIP codes within 16.9 miles

Population affected: 1,417,163
Severity score: 1,147,902,030
Shared water system detected — multiple ZIPs served by the same utility
Cross-state cluster: NC, SC
ZIP codes: 28054, 28056, 28098, 28201, 28202, 28203, 28204, 28205, 28206, 28207, 28208, 28209, 28210, 28211, 28212, 28213, 28214, 28215, 28216, 28217 ... and 61 more

#20: Indianapolis, IN

Health Violations — 71 ZIP codes within 17.6 miles

Population affected: 2,864,643
Severity score: 1,016,948,265
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 46032, 46033, 46037, 46038, 46060, 46061, 46062, 46082, 46085, 46201, 46202, 46203, 46204, 46205, 46206, 46207, 46208, 46209, 46211, 46213 ... and 51 more

#21: League City, TX

Health Violations — 20 ZIP codes within 13.8 miles

Population affected: 4,505,405
Severity score: 901,081,000
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 77034, 77058, 77059, 77062, 77075, 77089, 77260, 77510, 77511, 77512, 77517, 77539, 77563, 77573, 77574, 77581, 77584, 77588, 77590, 77591

#22: Syracuse, NY

Health Violations — 37 ZIP codes within 15.5 miles

Population affected: 2,335,117
Severity score: 863,993,290
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 13060, 13066, 13080, 13088, 13089, 13090, 13135, 13138, 13152, 13201, 13202, 13203, 13204, 13205, 13206, 13207, 13208, 13209, 13210, 13211 ... and 17 more

#23: Longmeadow, MA

Health Violations — 38 ZIP codes within 19.5 miles

Population affected: 2,189,264
Severity score: 831,920,320
Shared water system detected — multiple ZIPs served by the same utility
Cross-state cluster: CT, MA
ZIP codes: 01085, 01101, 01102, 01103, 01104, 01105, 01106, 01107, 01108, 01109, 01111, 01115, 01116, 01118, 01119, 01128, 01129, 01133, 01138, 01139 ... and 18 more

#24: Buffalo, NY

Health Violations — 47 ZIP codes within 15.7 miles

Population affected: 3,430,164
Severity score: 806,088,540
Shared water system detected — multiple ZIPs served by the same utility
ZIP codes: 14033, 14052, 14127, 14201, 14202, 14203, 14204, 14205, 14206, 14207, 14208, 14209, 14210, 14211, 14212, 14213, 14214, 14215, 14216, 14217 ... and 27 more

#25: Stamford, CT

Health Violations — 48 ZIP codes within 22.1 miles

Population affected: 1,564,201
Severity score: 750,816,480
Shared water system detected — multiple ZIPs served by the same utility
Cross-state cluster: CT, NY
ZIP codes: 06801, 06810, 06811, 06813, 06814, 06816, 06817, 06850, 06851, 06852, 06853, 06854, 06855, 06856, 06857, 06858, 06859, 06860, 06901, 06902 ... and 28 more

Data from EPA SDWIS. Clusters generated 2026-06-03. Algorithm: 15-mile neighbor radius, 30-mile max diameter, minimum 3 ZIPs. Population deduplicated by water system ID.