F0/100
Boulder Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 1,400 residents · Montana
What's In Boulder's Tap Water?
2
Contaminants Tested
1
Exceed EPA Limits
0
Above EPA Goals
1 contaminant above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.40 mg/L | 1.30 mg/L | Over Limit |
EPA Violation History
3
Violations (last 5yr)
0
Unresolved
1
Health-Related
TIER 3Resolved
Failed Level 2 Assessment under Revised Total Coliform Rule
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: January 1, 2024 – December 31, 2024Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 3Resolved
Failed Level 2 Assessment under Revised Total Coliform Rule
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
When: January 1, 2024 – December 31, 2024Rule: Stage 2 DBPREnforcement: Resolving — corrective action underway
TIER 2Resolved
Violation related to Coliform (pre-2016 TCR)
When: July 1, 2022 – July 28, 2022Rule: Surface Water Treatment RuleEnforcement: Resolving — corrective action underway
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
BOULDER CITY OF
Population Served
1,400
Water Source
Groundwater
System ID
MT0000158
Frequently Asked Questions About Boulder Water
Is Boulder tap water safe to drink?
Boulder, Montana tap water receives a grade of F (0/100), which is considered failing. 1 contaminant(s) exceed EPA maximum contaminant levels and 87 violation(s) are on record. Residents should consider using an NSF-certified water filter to reduce contaminant exposure.
What contaminants are in Boulder's water?
Of the 2 contaminants tested in Boulder's water supply, the most notable include Copper (90th percentile). 1 contaminant(s) exceed EPA legal limits (MCLs). 1 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Boulder have any water quality violations?
Yes, Boulder has 87 EPA violation(s) on record, with the most recent in 2024. Violation types include MR, TT, MON. 6 of these are health-based violations, which are the most serious category.
Do I need a water filter in Boulder?
Based on EPA data, using a water filter in Boulder is recommended. 1 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does Boulder's tap water come from?
Boulder's drinking water is sourced from groundwater and supplied by BOULDER CITY OF. The system serves approximately 1,400 people. Groundwater is pumped from underground aquifers, which often provides natural filtration.
How often is Boulder'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. Boulder'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 Boulder's water compare to other cities in Montana?
Boulder's water quality score of 0/100 earns a grade of F, which is considered failing. This is a concerning score that suggests significant water quality issues. Visit our Montana state page to see how all cities in the state compare.
What should I do if I'm concerned about Boulder's water quality?
If you have concerns about Boulder'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 (BOULDER CITY OF) 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.