Is Challis, ID Tap Water Safe to Drink?
Graded B, with 6 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
76.9/100
waterverge.com Challis, ID — Water Quality Report
Challis's drinking water received a grade of B (76.9 out of 100), indicating good water quality. The city's 2 water systems serve approximately 1,025 residents using surface water.
Lead levels were measured at 5.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 134 violations on record, including 8 health-based violations. 6 remain unresolved.
What to know about Challis's water
Challis ranks #61 out of 139 cities in Idaho for water quality, placing it mid-range in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
As a small community water system, Challis may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 12 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Challis, ID water safe to drink?
Challis's drinking water has significant quality concerns based on EPA testing data. With a grade of B (76.9/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 1,025 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Challis
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Challis's water quality assessment. Grade: B (76.9/100).
Contaminants: CARBON, TOTAL.
Contaminants: Revised Total Coliform Rule.
Contaminants: Revised Total Coliform Rule.
Federal disaster declaration (FEMA DR-4333). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-3244). Hurricane event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Challis's water supply.
Well within EPA limits.
Violation history
Challis's water system has 134 total violations on record, including 8 health-based violations. 6 remain unresolved. 12 violations were issued in the last 5 years.
Flood & environmental risk
Custer County has experienced 2 federally declared disasters since 2005. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies.
Where does Challis's water come from?
Challis's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 2 water systems serving approximately 1,025 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment.
What Challis residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Challis's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Run cold water for 30 seconds before drinking, especially in the morning. Lead and copper leach from household plumbing when water sits in pipes.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Drought conditions
D1 — moderate droughtCuster County is currently in D1 (moderate drought) per the U.S. Drought Monitor (week of May 5, 2026). Drought can elevate disinfection-byproduct (TTHM/HAA5) levels and taste/odor issues as utilities draw from lower reservoirs.
Source: U.S. Drought Monitor, updated weekly by NDMC, USDA, and NOAA.
Flood & disaster history
Custer County has experienced 2 federally declared disasters since 2005. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 5.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Challis compares by contaminant
Explore where Challis ranks among all Idaho cities for specific contaminants.
Water source & infrastructure
Where Challis's water comes from
Challis's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 1,025 people through 2 water systems.
Water systems serving Challis
| System Name | PWSID | Population | Source |
|---|---|---|---|
| CHALLIS CITY OF | ID7190013 | 900 | SW |
| ROUND VALLEY WATER ASSN | ID7190042 | 125 | GW |
How Challis compares
Full Idaho rankings →Challis's score of 76.9/100 is above the average of 43/100 among major Idaho cities. It outscores 10 of 10 nearby cities.
Nearby cities
View Idaho rankings →About Challis, ID
Learn more about your water
Guides and resources related to Challis's water quality findings.
Explore water quality across Custer
Frequently asked questions
Is Challis, ID tap water safe to drink?
Challis's water quality earned a grade of B (76.9/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #61 out of 139 cities tested in Idaho.
What contaminants are in Challis's water?
Lead was measured at 5.0 ppb (90th percentile). 134 violations are on record.
How is Challis's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Challis?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Challis's water come from?
Challis's water is sourced from Surface water. The city has 2 water systems serving approximately 1,025 residents.
What health violations has Challis's water system had?
Challis has 8 health-based violations on record. The most recent violation was recorded in September 2024. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 6 violations remain unresolved.
How does Challis's water compare to other cities?
Challis ranks #61 out of 139 cities in Idaho (better than 56% of state cities) and #9161 out of 15744 cities nationally (42th percentile). The grade of B reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.