A83/100
Cottage Grove Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 9,345 residents · Wisconsin
What's In Cottage Grove's Tap Water?
51
Contaminants Tested
0
Exceed EPA Limits
1
Above EPA Goals
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Lead (90th percentile) | 0.002 mg/L | 0.015 mg/L | Above Goal |
EPA Violation History
2
Violations (last 5yr)
1
Unresolved
1
Health-Related
TIER 2Resolved
Treatment technique violation
When: October 17, 2024 – February 24, 2025Rule: Ground Water RuleEnforcement: Resolving — corrective action underway
TIER 3Unresolved
Disinfection byproduct treatment technique failure
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
COTTAGE GROVE WATERWORKS
Population Served
9,345
Water Source
Groundwater
System ID
WI1130218
Frequently Asked Questions About Cottage Grove Water
Is Cottage Grove tap water safe to drink?
Cottage Grove, Wisconsin tap water receives a grade of A (83/100), which is considered excellent. Out of 51 contaminants tested, none exceed EPA maximum contaminant levels (MCLs) and 1 exceed health guidelines (MCLGs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in Cottage Grove's water?
Of the 51 contaminants tested in Cottage Grove's water supply, the most notable include Lead (90th percentile). No contaminants exceed EPA legal limits. 1 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Cottage Grove have any water quality violations?
Yes, Cottage Grove has 6 EPA violation(s) on record, with the most recent in 2024. Violation types include TT, Other, MR. 2 of these are health-based violations, which are the most serious category.
Do I need a water filter in Cottage Grove?
Cottage Grove water meets EPA standards, so a filter is not strictly necessary. However, some residents prefer the added security of a water filter. EPA health goals (MCLGs) are stricter than legal limits and are set at levels with zero expected health risk. 1 contaminant(s) exceed these stricter goals.
Where does Cottage Grove's tap water come from?
Cottage Grove's drinking water is sourced from groundwater and supplied by COTTAGE GROVE WATERWORKS. The system serves approximately 9,345 people. Groundwater is pumped from underground aquifers, which often provides natural filtration.
How often is Cottage Grove's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Cottage Grove's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does Cottage Grove's water compare to other cities in Wisconsin?
Cottage Grove's water quality score of 83/100 earns a grade of A, which is considered excellent. This places Cottage Grove among the better-performing water systems in Wisconsin. Visit our Wisconsin state page to see how all cities in the state compare.
What should I do if I'm concerned about Cottage Grove's water quality?
If you have concerns about Cottage Grove's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (COTTAGE GROVE WATERWORKS) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.