Systems with a yearly average above an EPA comparison level
9.2%18 of 196 active community water systems
All 196 systems met the sampling requirement for a yearly average. Of those systems, 18 had at least one yearly average above an EPA comparison level and 178 did not.
EPA-based study benchmark: a fixed, unrounded research cutoff used to reproduce EPA’s final UCMR 5 technical-assistance classification based on the April 2024 federal levels. It is not a current federal or state standard. The label does not determine compliance, household exposure, or health risk.
State rules: The labels on this page use fixed research cutoffs based on the April 2024 federal levels. Wisconsin may use different current standards or guidance. These UCMR 5 results do not determine current federal or state compliance. Find the official Wisconsin drinking-water program →
Check your area
Find your water system
A ZIP code finds possible public water systems for an area; it cannot identify the supplier for a specific home. Confirm the provider using a water bill or utility record.
Compound summary
System counts in Wisconsin
Each count shows how many included water systems had a yearly average above the named EPA comparison level.
| EPA rounding cutoff | Systems above comparison level | Water systems included | Percent |
|---|---|---|---|
| PFOA: 4 ppt level; unrounded average ≥4.05 ppt after applying EPA rounding | 12 | 196 | 6.1% |
| PFOS: 4 ppt level; unrounded average ≥4.05 ppt after applying EPA rounding | 12 | 196 | 6.1% |
| PFHxS: 10 ppt level; unrounded average ≥15 ppt after applying EPA rounding | 3 | 196 | 1.5% |
| PFNA: 10 ppt level; unrounded average ≥15 ppt after applying EPA rounding | 0 | 196 | 0.0% |
| HFPO-DA: 10 ppt level; unrounded average ≥15 ppt after applying EPA rounding | 0 | 196 | 0.0% |
| Hazard Index: 1 level; unrounded index ≥1.5 and at least two detected components | 3 | 196 | 1.5% |
System directory
Community water systems with complete monitoring
“Complete monitoring” means at least one sampling location had every required sample needed to calculate a yearly average. It does not mean every location or home was tested. Each PWSID appears once, preventing double counting across ZIP associations.
| Public water system | PWSID | Population served | Primary source | Sampling locations | EPA comparison result |
|---|---|---|---|---|---|
| ALLOUEZ WATERWORKS | WI4050455 | 13,923 | Surface water purchased | 1 | No available average above comparison levels |
| ALTOONA WATERWORKS | WI6180280 | 9,627 | Ground water | 6 | No available average above comparison levels |
| ANTIGO WATERWORKS | WI7340086 | 7,780 | Ground water | 1 | No available average above comparison levels |
| APPLETON WATERWORKS | WI4450333 | 74,511 | Surface water | 1 | No available average above comparison levels |
| ARENA WATERWORKS | WI1250073 | 877 | Ground water | 1 | No available average above comparison levels |
| ASHLAND WATER UTILITY | WI8020373 | 8,000 | Surface water | 1 | No available average above comparison levels |
| ASHWAUBENON WATERWORKS | WI4050456 | 17,730 | Surface water purchased | 1 | No available average above comparison levels |
| BALDWIN WATERWORKS | WI6560119 | 4,440 | Ground water | 2 | No available average above comparison levels |
| BARABOO WATERWORKS | WI1570085 | 12,703 | Ground water | 5 | No available average above comparison levels |
| BARRON LIGHT & WATER DEPT | WI6030125 | 3,423 | Ground water | 4 | No available average above comparison levels |
| BEAVER DAM WATER UTILITY | WI1140059 | 16,200 | Ground water | 1 | No available average above comparison levels |
| BELLEVUE WATERWORKS | WI4050459 | 16,715 | Surface water purchased | 1 | No available average above comparison levels |
| BELOIT CITY OF | WI1540112 | 36,677 | Ground water | 7 | No available average above comparison levels |
| BERLIN WATERWORKS | WI4240216 | 5,524 | Ground water | 3 | No available average above comparison levels |
| BLACK RIVER FALLS WATERWORKS | WI6270244 | 3,608 | Ground water | 4 | No available average above comparison levels |
| BLOOMER WATERWORKS | WI6090448 | 3,680 | Ground water | 4 | No available average above comparison levels |
| BLOOMFIELD, VILLAGE OF | WI2651469 | 4,071 | Ground water | 2 | No available average above comparison levels |
| BLOOMINGTON WATERWORKS | WI1220085 | 682 | Ground water | 1 | No available average above comparison levels |
| BRILLION WATERWORKS | WI4080221 | 3,262 | Ground water | 3 | No available average above comparison levels |
| BROOKFIELD WATER UTILITY | WI2680253 | 29,070 | Ground water | 17 | No available average above comparison levels |
| BROWN DEER WATERWORKS | WI2410556 | 12,741 | Surface water purchased | 1 | No available average above comparison levels |
| BURLINGTON WATERWORKS | WI2520177 | 11,043 | Ground water | 5 | No available average above comparison levels |
| CALEDONIA WATER UTILITY - VILLAGE OF | WI2520184 | 21,819 | Surface water purchased | 2 | No available average above comparison levels |
| CEDARBURG L & W COMMISSION | WI2460108 | 12,500 | Ground water | 4 | No available average above comparison levels |
| CHILTON WATERWORKS | WI4080222 | 4,191 | Ground water | 1 | No available average above comparison levels |
| CHIPPEWA FALLS WATERWORKS | WI6090456 | 13,375 | Ground water | 2 | No available average above comparison levels |
| CLINTON WATERWORKS, WI | WI1540114 | 2,119 | Ground water | 2 | No available average above comparison levels |
| CLINTONVILLE UTILITIES | WI4690391 | 4,635 | Ground water | 3 | No available average above comparison levels |
| COLUMBUS WATER & LIGHT DEPARTMENT | WI1110038 | 5,173 | Ground water | 2 | No available average above comparison levels |
| COMBINED LOCKS WATERWORKS | WI4450409 | 3,609 | Ground water purchased | 1 | No available average above comparison levels |
| COTTAGE GROVE WATERWORKS | WI1130218 | 9,345 | Ground water | 3 | No available average above comparison levels |
| CROSS PLAINS WATERWORKS | WI1130219 | 4,100 | Ground water | 3 | No available average above comparison levels |
| CUDAHY WATERWORKS | WI2410169 | 18,659 | Surface water | 1 | No available average above comparison levels |
| DARBOY SANITARY DIST 1 | WI4450117 | 13,024 | Ground water | 2 | No available average above comparison levels |
| DE PERE WATER DEPARTMENT | WI4050453 | 25,660 | Surface water purchased | 1 | No available average above comparison levels |
| DEFOREST WATERWORKS | WI1130221 | 10,500 | Ground water | 4 | No available average above comparison levels |
| DELAVAN WATERWORKS | WI2650113 | 9,028 | Ground water | 3 | No available average above comparison levels |
| DENMARK WATERWORKS | WI4050351 | 2,684 | Surface water purchased | 2 | No available average above comparison levels |
| DODGEVILLE WATERWORKS | WI1250079 | 4,583 | Ground water | 4 | No available average above comparison levels |
| EAST TROY WATERWORKS | WI2650123 | 5,054 | Ground water | 4 | No available average above comparison levels |
| EAU CLAIRE WATERWORKS | WI6180230 | 70,587 | Ground water | 1 | No available average above comparison levels |
| EDGERTON WATERWORKS | WI1540119 | 5,512 | Ground water | 3 | No available average above comparison levels |
| ELKHORN WATERWORKS | WI2650062 | 10,317 | Ground water | 3 | No available average above comparison levels |
| ELLSWORTH WATERWORKS | WI6480239 | 3,304 | Ground water | 3 | No available average above comparison levels |
| EVANSVILLE WATERWORKS | WI1540047 | 5,703 | Ground water | 2 | No available average above comparison levels |
| FITCHBURG UTILITY DIST 1 | WI1130231 | 24,500 | Ground water | 4 | No available average above comparison levels |
| FOND DU LAC WATERWORKS | WI4200469 | 44,678 | Ground water | 4 | No available average above comparison levels |
| FOREST JUNCTION PUB UTIL | WI4080377 | 487 | Ground water | 2 | No available average above comparison levels |
| FORT ATKINSON WATERWORKS | WI1280103 | 12,390 | Ground water | 4 | No available average above comparison levels |
| FORT MCCOY NORTH POST | WI6420302 | 10,000 | Ground water | 6 | No available average above comparison levels |
| FOX CROSSING UTILITIES EAST-FORMERLY MENASHA TN OF | WI4710453 | 10,927 | Surface water purchased | 2 | No available average above comparison levels |
| FOX CROSSING UTILITIES WEST-FORMERLY MENASHA TN OF | WI4710358 | 14,000 | Ground water | 4 | No available average above comparison levels |
| FOX POINT WATERWORKS | WI2410584 | 6,808 | Surface water purchased | 1 | No available average above comparison levels |
| FRANKLIN WATER UTILITY | WI2410563 | 22,500 | Surface water purchased | 1 | No available average above comparison levels |
| GERMANTOWN WATER UTILITY | WI2670105 | 20,027 | Ground water | 6 | No available average above comparison levels |
| GLENDALE WATERWORKS | WI2410168 | 12,883 | Surface water purchased | 1 | No available average above comparison levels |
| GRAFTON WATERWORKS | WI2460111 | 12,269 | Ground water | 6 | No available average above comparison levels |
| GRAND CHUTE TN SAN DIST 1 | WI4450429 | 21,583 | Surface water purchased | 1 | No available average above comparison levels |
| GREEN BAY WATERWORKS | WI4050356 | 107,369 | Surface water | 1 | No available average above comparison levels |
| GREENDALE WATERWORKS | WI2410571 | 14,393 | Surface water purchased | 1 | No available average above comparison levels |
| GREENVILLE SANITARY DIST | WI4450278 | 11,340 | Ground water | 4 | No available average above comparison levels |
| HARRISON UTILITIES - FKA WAVERLY SD | WI4080076 | 5,500 | Surface water purchased | 1 | No available average above comparison levels |
| HARTFORD WATERWORKS, WI | WI2670110 | 15,805 | Ground water | 5 | Above an EPA comparison level |
| HARTLAND WATERWORKS | WI2680205 | 9,212 | Ground water | 5 | Above an EPA comparison level |
| HILBERT WATERWORKS | WI4080269 | 1,176 | Ground water | 2 | No available average above comparison levels |
| HOLMEN WATERWORKS | WI6320306 | 10,147 | Ground water | 4 | No available average above comparison levels |
| HORICON WATERWORKS | WI1140146 | 3,682 | Ground water | 3 | No available average above comparison levels |
| HOWARD WATERWORKS | WI4050468 | 21,133 | Surface water purchased | 2 | No available average above comparison levels |
| HUDSON WATERWORKS | WI6560087 | 18,558 | Ground water | 7 | No available average above comparison levels |
| JACKSON WATERWORKS | WI2670111 | 7,844 | Ground water | 4 | No available average above comparison levels |
| JANESVILLE WATER UTILITY | WI1540127 | 64,415 | Ground water | 3 | No available average above comparison levels |
| JEFFERSON WATERWORKS | WI1280104 | 7,926 | Ground water | 3 | No available average above comparison levels |
| KAUKAUNA UTILITIES | WI4450336 | 17,493 | Ground water | 3 | No available average above comparison levels |
| KENOSHA WATER UTILITY | WI2300046 | 99,218 | Surface water | 1 | No available average above comparison levels |
| KESHENA | 055295508 | 3,960 | Ground water | 1 | No available average above comparison levels |
| KEWASKUM WATERWORKS | WI2670112 | 4,309 | Ground water | 4 | Above an EPA comparison level |
| KIEL WATERWORKS | WI4360427 | 3,932 | Ground water | 4 | No available average above comparison levels |
| KIMBERLY WATERWORKS | WI4450342 | 7,608 | Ground water | 3 | No available average above comparison levels |
| KRONENWETTER WATER & SEWER UTILITY | WI7371700 | 6,931 | Ground water | 2 | No available average above comparison levels |
| LA CROSSE WATERWORKS | WI6320309 | 53,000 | Ground water | 10 | Above an EPA comparison level |
| LAC DU FLAMBEAU | 055295401 | 2,962 | Ground water | 2 | No available average above comparison levels |
| LAKE GENEVA UTILITY COMMISSION | WI2650066 | 7,107 | Ground water | 2 | Above an EPA comparison level |
| LAKE HALLIE WATERWORKS VILLAGE OF | WI6090849 | 6,701 | Ground water | 4 | No available average above comparison levels |
| LAKE MILLS WATERWORKS | WI1280108 | 6,211 | Ground water | 3 | No available average above comparison levels |
| LANCASTER WATERWORKS | WI1220107 | 3,907 | Ground water | 3 | No available average above comparison levels |
| LAWRENCE WATERWORKS | WI4051625 | 5,398 | Surface water purchased | 1 | No available average above comparison levels |
| LEDGEVIEW TN SANITARY DIST 2 | WI4051418 | 7,602 | Surface water purchased | 2 | No available average above comparison levels |
| LITTLE CHUTE WATERWORKS | WI4450338 | 12,168 | Ground water | 3 | No available average above comparison levels |
| MADISON WATER UTILITY | WI1130224 | 272,000 | Ground water | 20 | No available average above comparison levels |
| MANITOWOC WATERWORKS | WI4360364 | 34,500 | Surface water | 1 | No available average above comparison levels |
| MARINETTE WATERWORKS | WI4380395 | 10,968 | Surface water | 1 | No available average above comparison levels |
| MARSHALL WATERWORKS | WI1130237 | 3,862 | Ground water | 3 | No available average above comparison levels |
| MARSHFIELD UTILITIES | WI7720165 | 18,815 | Ground water | 3 | Above an EPA comparison level |
| MAUSTON GREEN ACRES | WI7290134 | 40 | Ground water | 1 | No available average above comparison levels |
| MAUSTON WATERWORKS | WI7290129 | 4,456 | Ground water | 3 | No available average above comparison levels |
| MAYVILLE WATERWORKS | WI1140057 | 5,112 | Ground water | 4 | No available average above comparison levels |
| MCFARLAND WATERWORKS | WI1130241 | 9,676 | Ground water | 3 | No available average above comparison levels |
| MEDFORD WATERWORKS | WI8610125 | 4,318 | Ground water | 6 | No available average above comparison levels |
| MENASHA ELEC & WATER UTIL | WI4710334 | 15,144 | Surface water | 1 | No available average above comparison levels |
| MENOMONEE FALLS WW - SURFACE WATER | WI2680082 | 23,867 | Surface water purchased | 1 | No available average above comparison levels |
| MENOMONIE WATERWORKS | WI6170268 | 15,950 | Ground water | 3 | No available average above comparison levels |
| MEQUON WATER UTILITY | WI2460112 | 11,152 | Surface water purchased | 2 | No available average above comparison levels |
| MERRILL WATERWORKS | WI7350123 | 9,661 | Ground water | 2 | No available average above comparison levels |
| MIDDLETON WATERWORKS | WI1130242 | 23,868 | Ground water | 6 | No available average above comparison levels |
| MILTON WATERWORKS | WI1540130 | 5,588 | Ground water | 4 | No available average above comparison levels |
| MILWAUKEE WATERWORKS | WI2410100 | 626,000 | Surface water | 2 | No available average above comparison levels |
| MONONA WATERWORKS | WI1130245 | 8,624 | Ground water | 3 | No available average above comparison levels |
| MONROE WATERWORKS | WI1230078 | 10,780 | Ground water | 5 | No available average above comparison levels |
| MT HOREB WATERWORKS | WI1130247 | 7,756 | Ground water | 4 | No available average above comparison levels |
| MUKWONAGO WATERWORKS | WI2680209 | 8,190 | Ground water | 2 | No available average above comparison levels |
| MUSKEGO WATER UTILITY | WI2681741 | 8,150 | Ground water | 8 | No available average above comparison levels |
| NEENAH WATERWORKS | WI4710348 | 27,506 | Surface water | 1 | No available average above comparison levels |
| NEW BERLIN WATER UTILITY | WI2680217 | 27,899 | Surface water purchased | 1 | No available average above comparison levels |
| NEW LONDON WATERWORKS | WI4690398 | 7,187 | Ground water | 7 | No available average above comparison levels |
| NEW RICHMOND WATERWORKS | WI6560126 | 10,824 | Ground water | 5 | No available average above comparison levels |
| NORTH FOND DU LAC WATERWORKS | WI4200405 | 5,414 | Ground water | 1 | No available average above comparison levels |
| NORTH SHORE WATER COMMISSION | WI2413515 | 35,598 | Surface water | 1 | No available average above comparison levels |
| OAK CREEK WATERWORKS | WI2410172 | 32,104 | Surface water | 1 | No available average above comparison levels |
| OCONOMOWOC WATERWORKS | WI2680227 | 15,805 | Ground water | 4 | No available average above comparison levels |
| OCONTO WATERWORKS | WI4430495 | 4,583 | Ground water | 3 | No available average above comparison levels |
| OMRO WATERWORKS | WI4710357 | 3,629 | Ground water | 3 | No available average above comparison levels |
| ONALASKA WATERWORKS | WI6320327 | 18,000 | Ground water | 4 | No available average above comparison levels |
| ONEIDA #1 OR SITE #1 | 055295703 | 4,393 | Ground water | 2 | No available average above comparison levels |
| OREGON WATERWORKS | WI1130251 | 11,200 | Ground water | 3 | No available average above comparison levels |
| OSHKOSH WATERWORKS | WI4710457 | 63,000 | Surface water | 1 | No available average above comparison levels |
| PALMYRA WATERWORKS | WI1280112 | 1,756 | Ground water | 2 | Above an EPA comparison level |
| PESHTIGO WATERWORKS | WI4380442 | 3,420 | Ground water | 3 | No available average above comparison levels |
| PEWAUKEE CITY WATER AND SEWER UTILITY | WI2680214 | 8,671 | Ground water | 8 | Above an EPA comparison level |
| PEWAUKEE VILLAGE WATERWORKS | WI2680229 | 8,166 | Ground water | 5 | No available average above comparison levels |
| PLATTEVILLE WATERWORKS | WI1220115 | 12,268 | Ground water | 3 | No available average above comparison levels |
| PLEASANT PRAIRIE WATER UTILITY | WI2300167 | 10,754 | Surface water purchased | 1 | No available average above comparison levels |
| PLOVER WATERWORKS | WI7500726 | 13,486 | Ground water | 3 | No available average above comparison levels |
| PLYMOUTH UTILITIES | WI4600446 | 8,964 | Ground water | 7 | No available average above comparison levels |
| PORT WASHINGTON WATERWORKS | WI2460054 | 12,853 | Surface water | 1 | No available average above comparison levels |
| PORTAGE WATERWORKS | WI1110039 | 10,437 | Ground water | 2 | No available average above comparison levels |
| PRAIRIE DU CHIEN WATERWORKS | WI6120250 | 6,005 | Ground water | 3 | Above an EPA comparison level |
| PRAIRIE DU SAC WATERWORKS | WI1570100 | 4,006 | Ground water | 2 | No available average above comparison levels |
| PRESCOTT WATERWORKS | WI6480243 | 4,258 | Ground water | 2 | Above an EPA comparison level |
| PULASKI WATERWORKS | WI4050355 | 4,040 | Ground water | 2 | No available average above comparison levels |
| RACINE WATERWORKS | WI2520062 | 105,100 | Surface water | 1 | No available average above comparison levels |
| REEDSBURG WATERWORKS | WI1570102 | 9,984 | Ground water | 5 | No available average above comparison levels |
| RHINELANDER WATER & WASTEWATER | WI7440126 | 8,234 | Ground water | 2 | Above an EPA comparison level |
| RIB MOUNTAIN SANITARY DIST | WI7370660 | 6,398 | Ground water | 4 | Above an EPA comparison level |
| RICE LAKE WATERWORKS | WI6030138 | 9,012 | Ground water | 4 | No available average above comparison levels |
| RICHLAND CENTER WATERWORKS | WI1530068 | 5,100 | Ground water | 3 | No available average above comparison levels |
| RIPON WATER UTILITY | WI4200476 | 7,716 | Ground water | 4 | No available average above comparison levels |
| RIVER FALLS WATERWORKS | WI6480246 | 16,000 | Ground water | 5 | No available average above comparison levels |
| SAUK CITY WATERWORKS | WI1570105 | 3,518 | Ground water | 2 | No available average above comparison levels |
| SAUKVILLE WATERWORKS | WI2460134 | 4,268 | Ground water | 5 | Above an EPA comparison level |
| SCHOFIELD WATERWORKS | WI7370162 | 2,205 | Ground water | 2 | Above an EPA comparison level |
| SEYMOUR WATERWORKS | WI4450337 | 3,601 | Ground water | 2 | No available average above comparison levels |
| SHAWANO LK SAN DIST 1 | WI4590457 | 4,950 | Ground water | 3 | No available average above comparison levels |
| SHAWANO WATERWORKS | WI4590456 | 9,610 | Ground water | 3 | No available average above comparison levels |
| SHEBOYGAN FALLS UTILITIES | WI4600455 | 8,687 | Surface water purchased | 1 | No available average above comparison levels |
| SHEBOYGAN TN WATERWORKS | WI4600403 | 4,596 | Ground water | 3 | No available average above comparison levels |
| SHEBOYGAN WATER UTILITIES | WI4600354 | 49,931 | Surface water | 1 | No available average above comparison levels |
| SHOREWOOD WATERWORKS | WI2410607 | 13,535 | Surface water purchased | 1 | No available average above comparison levels |
| SHULLSBURG WATERWORKS | WI1330076 | 1,222 | Ground water | 2 | No available average above comparison levels |
| SLINGER WATER UTILITY | WI2670116 | 5,659 | Ground water | 3 | No available average above comparison levels |
| SOMERS WATER UTILITY | WI2301421 | 1,930 | Surface water purchased | 1 | No available average above comparison levels |
| SOUTH MILWAUKEE WATERWORKS | WI2410144 | 21,340 | Surface water | 1 | No available average above comparison levels |
| SOUTH-CENTRAL WATER SYSTEM | 055295003 | 2,805 | Ground water | 1 | No available average above comparison levels |
| SPARTA WATERWORKS | WI6420297 | 10,025 | Ground water | 5 | No available average above comparison levels |
| STANLEY WATERWORKS | WI6090462 | 3,500 | Ground water | 3 | No available average above comparison levels |
| STEVENS POINT WATERWORKS | WI7500141 | 26,717 | Ground water | 2 | No available average above comparison levels |
| STOUGHTON WATERWORKS | WI1130078 | 13,078 | Ground water | 4 | No available average above comparison levels |
| STURGEON BAY WATERWORKS | WI4150526 | 9,700 | Ground water | 5 | Above an EPA comparison level |
| SUAMICO WATERWORKS | WI4051031 | 4,697 | Ground water | 2 | No available average above comparison levels |
| SUN PRAIRIE UTILITIES | WI1130258 | 39,300 | Ground water | 7 | No available average above comparison levels |
| SUPERIOR WATER LIGHT & POWER COMPANY | WI8160147 | 26,084 | Surface water | 1 | No available average above comparison levels |
| SUSSEX VILLAGE HALL & WATER UTILITY | WI2680233 | 11,750 | Ground water | 4 | No available average above comparison levels |
| TOMAH WATERWORKS | WI6420254 | 9,192 | Ground water | 5 | No available average above comparison levels |
| TOMAHAWK WATERWORKS | WI7350127 | 3,180 | Ground water | 2 | Above an EPA comparison level |
| TOWN OF BROOKFIELD SAN DIST 4 | WI2680239 | 6,419 | Ground water | 3 | No available average above comparison levels |
| TWO RIVERS WATERWORKS | WI4360436 | 11,270 | Surface water | 1 | No available average above comparison levels |
| UNION GROVE WATERWORKS | WI2520200 | 4,900 | Ground water | 3 | No available average above comparison levels |
| VERONA WATERWORKS | WI1130259 | 14,030 | Ground water | 5 | No available average above comparison levels |
| VIROQUA WATERWORKS | WI6630263 | 4,362 | Ground water | 3 | No available average above comparison levels |
| WATERFORD ON THE BAY | WI8040687 | 45 | Ground water | 1 | No available average above comparison levels |
| WATERFORD WATERWORKS | WI2520202 | 5,368 | Ground water | 3 | No available average above comparison levels |
| WATERLOO WATERWORKS | WI1280115 | 3,520 | Ground water | 3 | No available average above comparison levels |
| WATERTOWN WATERWORKS | WI1280044 | 23,945 | Ground water | 3 | No available average above comparison levels |
| WAUKESHA WATER UTILITY | WI2680238 | 70,718 | Surface water purchased | 7 | No available average above comparison levels |
| WAUNAKEE WATERWORKS | WI1130265 | 14,879 | Ground water | 4 | No available average above comparison levels |
| WAUPACA WATERWORKS | WI4690402 | 6,062 | Ground water | 6 | Above an EPA comparison level |
| WAUPUN CORRECTIONAL INST | WI1140142 | 3,706 | Ground water | 2 | No available average above comparison levels |
| WAUPUN UTILITIES | WI1140131 | 8,056 | Ground water | 1 | No available average above comparison levels |
| WAUSAU WATERWORKS | WI7370102 | 39,994 | Ground water | 2 | No available average above comparison levels |
| WAUWATOSA WATERWORKS | WI2410596 | 49,064 | Surface water purchased | 1 | No available average above comparison levels |
| WEST ALLIS WATERWORKS | WI2410595 | 63,240 | Surface water purchased | 1 | No available average above comparison levels |
| WEST BEND WATERWORKS | WI2670120 | 31,752 | Ground water | 6 | No available average above comparison levels |
| WEST SALEM WATERWORKS | WI6320334 | 5,045 | Ground water | 3 | No available average above comparison levels |
| WESTON MUNICIPAL UTILITIES | WI7370163 | 16,000 | Ground water | 7 | Above an EPA comparison level |
| WHITEFISH BAY WATERWORKS | WI2410597 | 14,272 | Surface water purchased | 1 | No available average above comparison levels |
| WHITEWATER WATERWORKS | WI2650056 | 14,000 | Ground water | 5 | No available average above comparison levels |
| WIS RAPIDS WATER WORKS & LIGHTING COMM | WI7720108 | 20,000 | Ground water | 1 | No available average above comparison levels |
How the count works
What is included
Each active community water system with enough required samples for a yearly average is counted once, even if it is linked with several ZIP codes. Private wells are excluded, and UCMR 5 did not comprehensively monitor every small system.