O

Ontario, WI

—no score

Contamination score

Higher = more contaminated vs. other cities.

⚠️1 health-based violation on record.
0
Water sources
6
Violations
0
Pollution sources
0
Self-reported
0
Lawsuits

Share this with friends & family you care about ❤️

Help someone you love know what's in their water — we'll email them Ontario's report. No sign-ups, no list.

Reported illness & cancer claims

No claims reported yet. Be the first to add one.

Claims are aggregated from public records and community reports and may be unverified. If you believe your illness is linked to local water, request a consultation.

Self-reported issues

No issues reported yet. Be the first to report one.

Pollution sources & reported claims near your water

Factories, greenhouses, and contaminated sites mapped around the water supply. Tap any circle for detail.

Critical High Medium Reported claim

Get water alerts for Ontario, WI

We'll email you when a new violation, lawsuit, or health report appears for Ontario's water. Free, unsubscribe anytime.

Home water filtration system

Protect your home

Improve Ontario's water

A certified filtration system can remove lead, PFAS, nitrates, and the contaminants flagged on this page. Get a free, no-obligation quote tailored to your home.

What are you interested in?

By submitting you agree to be contacted about water treatment options.

Public water systems

Ontario Waterworks

PWSID:
WI6630259
Source:
Ground water
Serves:
554 people

EPA & DEP violations

Ontario Waterworks

PWSID WI66302596 violations

  • Revised Total Coliform Rule — MON violation

    medium severityResolved

    Revised Total Coliform Rule MON violation (Resolved).

    EPA SDWIS · MON · Began Jul 1, 2025 · 1 year ago · Source ↗

  • TTHM — MR violation

    medium severityArchived

    TTHM MR violation (Archived).

    EPA SDWIS · MR · Began Jan 1, 2025 · 1 year ago · Source ↗

  • Total Haloacetic Acids (HAA5) — MR violation

    medium severityArchived

    Total Haloacetic Acids (HAA5) MR violation (Archived).

    EPA SDWIS · MR · Began Jan 1, 2025 · 1 year ago · Source ↗

  • Public Notice — Other violation

    medium severityUnaddressed

    Public Notice Other violation (Unaddressed).

    EPA SDWIS · Other · Began Oct 17, 2024 · 1 year ago · Source ↗

  • LEAD AND COPPER RULE REVISIONS — TT violation

    high severityHealth-basedResolved

    LEAD AND COPPER RULE REVISIONS TT violation (Resolved).

    EPA SDWIS · TT · Began Oct 17, 2024 · 1 year ago · Source ↗

  • Violation — Violation violation

    medium severity

    Contaminant Violation violation.

    EPA SDWIS · Violation · Began — · Source ↗

Water-related lawsuits

No lawsuits on record.

In the news & sources

No coverage linked yet.