Is Arco, ID Tap Water Safe to Drink?
Graded A-, with 6 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
85.4/100
waterverge.com Arco, ID — Water Quality Report
Arco's drinking water received a grade of A- (85.4 out of 100), indicating good water quality. The city's 2 water systems serve approximately 1,139 residents using groundwater.
Lead levels were measured at 3.0 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 65 violations on record, including 12 health-based violations. 6 remain unresolved.
What to know about Arco's water
Arco ranks #44 out of 139 cities in Idaho for water quality, placing it mid-range in the state.
Arco relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff.
As a small community water system, Arco may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
Water quality score
See methodology →Is Arco, ID water safe to drink?
Arco's drinking water has significant quality concerns based on EPA testing data. With a grade of A- (85.4/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 1,139 residents using groundwater (wells).
Recent water quality updates for Arco
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Arco's water quality assessment. Grade: A- (85.4/100).
Contaminants: LEAD AND COPPER RULE REVISIONS, E. COLI.
1 health-based. Contaminants: Revised Total Coliform Rule.
Contaminants: Lead and Copper Rule.
Federal disaster declaration (FEMA DR-3244). Hurricane event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-186). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Arco's water supply.
Well within EPA limits.
Violation history
Arco's water system has 65 total violations on record, including 12 health-based violations. 6 remain unresolved. 3 violations were issued in the last 5 years.
Flood & environmental risk
Butte County has experienced 2 federally declared disasters since 1964. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Big Lost River Below Moore Div Nr Moore, Big Lost River, Big Lost River Nr Arco.
Where does Arco's water come from?
Arco's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 1,139 people. Groundwater is generally less susceptible to surface contamination but can contain naturally occurring contaminants like arsenic, radon, and nitrate. Nearby water bodies include Big Lost River Below Moore Div Nr Moore (river), Big Lost River (river), Big Lost River Nr Arco (river).
What Arco residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Arco'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.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Drought conditions
D2 — severe droughtButte County is currently in D2 (severe 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
Butte County has experienced 2 federally declared disasters since 1964. 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. | 3.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Arco compares by contaminant
Explore where Arco ranks among all Idaho cities for specific contaminants.
Water source & infrastructure
Where Arco's water comes from
Arco's drinking water is drawn from underground aquifers through wells.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals.
Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds.
The system is operated by local government ownership and serves approximately 1,139 people through 2 water systems.
Water bodies near Arco
Arco is located near 3 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Arco
| System Name | PWSID | Population | Source |
|---|---|---|---|
| ARCO CITY OF | ID6120001 | 1,080 | GW |
| BUTTE CITY OF | ID6120002 | 59 | GW |
How Arco compares
Full Idaho rankings →Arco's score of 85.4/100 is above the average of 43/100 among major Idaho cities. It outscores 10 of 10 nearby cities.
Nearby cities
View Idaho rankings →About Arco, ID
Learn more about your water
Guides and resources related to Arco's water quality findings.
Explore water quality across Butte
Frequently asked questions
Is Arco, ID tap water safe to drink?
Arco's water quality earned a grade of A- (85.4/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #44 out of 139 cities tested in Idaho.
What contaminants are in Arco's water?
Lead was measured at 3.0 ppb (90th percentile). 65 violations are on record.
How is Arco'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 Arco?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Arco's water come from?
Arco's water is sourced from Groundwater. The city has 2 water systems serving approximately 1,139 residents.
What health violations has Arco's water system had?
Arco has 12 health-based violations on record. The most recent violation was recorded in July 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 6 violations remain unresolved.
Is Arco's groundwater at risk of contamination?
Arco uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 65 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Arco's water compare to other cities?
Arco ranks #44 out of 139 cities in Idaho (better than 68% of state cities) and #5356 out of 15744 cities nationally (66th percentile). The grade of A- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.