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Ozaukee County, Wisconsin — public water systems

At a glance

249 active public water systems are filed under Ozaukee County, Wisconsin in EPA's SDWIS records, together reporting 92,392 people served. The largest is Port Washington Waterworks, which reports serving 12,853 people. 48 are community water systems serving people where they live; the other 201 are non-community systems, such as schools, workplaces, campgrounds and gas stations with their own supply.

Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.

Active systems

249

Population served

92.4K

Community systems

48

Groundwater share

99.2%

How does Ozaukee County compare with other Wisconsin counties?

Ozaukee County has the 8th-most active public water systems among the 90 counties listed for active Wisconsin systems in EPA records; among the 74 with 3 or more systems, the median has 140. Its systems report 92,392 people served in total, the 16th-largest county figure in the state and 1.8% of the statewide total. The average system here reports serving 371 people, about 21% below the Wisconsin average of 469. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.

Where does Ozaukee County's drinking water come from?

By primary water source, Ozaukee County's active systems draw on groundwater (247, 99%), surface water (1, 0.4%) and purchased surface water (1, 0.4%). Overall, 99% rely mainly on groundwater (including purchased groundwater) and 0.8% on surface water, compared with 99% and 0.6% across Wisconsin. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, Port Washington Waterworks, draws primarily on surface water.

What kinds of water systems operate in Ozaukee County?

Ozaukee County's active systems break down as 48 community systems (19%), 47 non-transient non-community systems (19%) and 154 transient non-community systems (62%). A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as private (88%), local government (9.6%) and state government (2.8%).

The 50 largest water systems in Ozaukee County

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Active public water systems in Ozaukee County, Wisconsin
#Water systemCountyPopulation servedTypeSource
1Port Washington WaterworksOzaukee12,853CommunitySurface water
2Cedarburg L & W CommissionOzaukee12,500CommunityGroundwater
3Grafton WaterworksOzaukee12,269CommunityGroundwater
4Mequon Water UtilityOzaukee11,152CommunityPurchased surface water
5Saukville WaterworksOzaukee4,268CommunityGroundwater
6Belgium WaterworksOzaukee2,493CommunityGroundwater
7Fredonia WaterworksOzaukee2,279CommunityGroundwater
8Homestead High SchoolOzaukee1,650Non-transient non-communityGroundwater
9Mcdonalds MequonOzaukee1,524Transient non-communityGroundwater
10Concordia UniversityOzaukee1,500CommunityGroundwater
11Walgreens in MequonOzaukee912Transient non-communityGroundwater
12Kwik TripOzaukee817Transient non-communityGroundwater
13Mequon Trail TownhomesOzaukee615CommunityGroundwater
14Christ Church MequonOzaukee600Transient non-communityGroundwater
15Huntington ParkOzaukee600CommunityGroundwater
16Christ Alone Lutheran School & ChurchOzaukee559Non-transient non-communityGroundwater
17Waynes Drive-inOzaukee510Transient non-communityGroundwater
18St Francis Borgia Catholic ChurchOzaukee510Transient non-communityGroundwater
19Missing Links Golf RangeOzaukee502Transient non-communityGroundwater
20Alliance Bible ChurchOzaukee457Transient non-communityGroundwater
21Village BpOzaukee452Transient non-communityGroundwater
22River Barn ParkOzaukee450Transient non-communityGroundwater
23St Francis Borgia Educational & Activity CenterOzaukee420Non-transient non-communityGroundwater
24Welcome MartOzaukee405Transient non-communityGroundwater
25Ozaukee Congreg Church & Parish HouseOzaukee402Transient non-communityGroundwater
26Ozaukee Congreg Fellowship HallOzaukee401Transient non-communityGroundwater
27Wi Dnr Harrington Beach Shower BldgOzaukee400Transient non-communityGroundwater
28Glen Oaks Office ParkOzaukee400Non-transient non-communityGroundwater
29Camp Jcc GymOzaukee368Transient non-communityGroundwater
30Hb Performance Systems Inc.Ozaukee315Non-transient non-communityGroundwater
31Portview ChurchOzaukee308Transient non-communityGroundwater
32J Mobil MequonOzaukee304Transient non-communityGroundwater
33Camp Jcc East End WellOzaukee300Transient non-communityGroundwater
34Kingdom Hall Jehovahs Witnesses - MequonOzaukee300Transient non-communityGroundwater
35Beechwood Farms EstatesOzaukee300CommunityGroundwater
36Bog Golf Course the BarnOzaukee300Transient non-communityGroundwater
37Westchester Lakes SubdivisionOzaukee300CommunityGroundwater
38Cedar Valley CheeseOzaukee265Non-transient non-communityGroundwater
39Park Place SubdivisionOzaukee260CommunityGroundwater
40Camp Jcc Pool & LodgeOzaukee258Transient non-communityGroundwater
41Cornerstone ChurchOzaukee253Transient non-communityGroundwater
42Trinity Ev Lutheran School & Church - FreistadtOzaukee250Non-transient non-communityGroundwater
43Reuter PavilionOzaukee250Transient non-communityGroundwater
44RiversiteOzaukee250Non-transient non-communityGroundwater
45Christian Life ChurchOzaukee229Transient non-communityGroundwater
46The Highland HouseOzaukee205Transient non-communityGroundwater
47Chucks PlaceOzaukee204Transient non-communityGroundwater
48Virmond ParkOzaukee200Transient non-communityGroundwater
49Covered Bridge ParkOzaukee200Transient non-communityGroundwater
50Brighton Ridge SubdivisionOzaukee200CommunityGroundwater

All other water systems in Ozaukee County (199)

The remaining active systems filed under Ozaukee County, largest first, with the population each reports serving.

Ozaukee County water systems: frequently asked questions

How many public water systems are in Ozaukee County, Wisconsin?

EPA's SDWIS records file 249 active public water systems under Ozaukee County, Wisconsin: 48 community systems (19%), 47 non-transient non-community systems (19%) and 154 transient non-community systems (62%).

Who supplies drinking water in Ozaukee County, WI?

The largest community water systems filed under Ozaukee County are Port Washington Waterworks (12,853 people served), Cedarburg L & W Commission (12,500 people served) and Grafton Waterworks (12,269 people served). Which system serves a particular address depends on its service area, which EPA's SDWIS records do not include; a water bill or the local utility can confirm it.

Does Ozaukee County's drinking water come from groundwater or surface water?

Of the 249 active public water systems in Ozaukee County, 99% draw mainly on groundwater and 0.8% on surface water, counting purchased supplies. The largest system, Port Washington Waterworks, uses surface water.

Where can I find a water quality report for Ozaukee County?

Each community water system must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1, covering the previous calendar year. 48 community systems are filed under Ozaukee County, so the report to look for is the one from the system that supplies your address.

How can I check violations for a water system in Ozaukee County?

Open the system's profile from the list on this page. Each profile shows the most recent Safe Drinking Water Act violations in EPA's records, with plain-English labels and whether each one is resolved. For current compliance status, EPA ECHO is the primary source.

More Wisconsin water systems

About this data

Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.

Cite as: AquaCensus, “Public water systems in Ozaukee County, Wisconsin”, https://aquacensus.com/water-systems/wisconsin/ozaukee (data as of October 1, 2026).