ONALASKA WATERWORKS: EPA violation history, explained

ONALASKA WATERWORKS has a health-based violation on record, but none in the last five years - an older issue, not necessarily a current one. 18,000 people get their water from it, across 5,110 connections.

Ranked against every other system in this dataset

Out of 12,903 systems in this dataset, ONALASKA WATERWORKS ranks 6,930th by violation burden (46th percentile) - 4 violations total, 2 health-baseds.

How ONALASKA WATERWORKS compares within WI

Among the 202 WI systems in this dataset, the average is 3.6 health-based violations - ONALASKA WATERWORKS's 2 is at or below that. The filter guide explains what a violation like this actually calls for.

Most recent violation on record

The last violation EPA has on record for ONALASKA WATERWORKS is from 2010-01-07 (health-based: 2010-01-07). Last reported to EPA: 05/29/2026.

What kind of problem, specifically

ONALASKA WATERWORKS's flagged contaminants and rule violations, grouped by what they actually mean for a filter choice rather than left as EPA's raw code list:

• Microbial contamination / treatment technique - flagged from: Coliform (TCR)

The most severe category on record is microbial contamination / treatment technique, which points toward a microbial-class filter if you want to address it directly.

What this data is and is not

This is what ONALASKA WATERWORKS reported to its state primacy agency and EPA under the Safe Drinking Water Act - real regulatory record, not a lab test of your specific tap. Water quality can still change between the meter and the faucet - household plumbing sits outside what a record of 4 logged violations can see. The guide to what this data misses covers that gap.