City of Twin Falls
EPA ID: ID5420058 · 56,121 people served · 4 ZIP codes
In the current EPA monitoring period, City of Twin Falls has 5 violations still listed as unresolved, with the utility supplying water to approximately 56,121 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Compliance Trajectory
Worsening · Risk tier: High · 95% chance of violation in next 12 months
Violations went from 3 (2021) to 4 (2024). The pattern suggests growing compliance challenges.
Service Area Map
Coverage area for City of Twin Falls Source: EPA SDWIS service area boundaries.
Service area boundary — Grade B
Service Area Demographics
The City of Twin Falls serves a community with a median household income of $62,273 and an estimated 78,502 residents across its service area. Approximately 58% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
City of Twin Falls's water is pumped from underground aquifers. Groundwater is naturally filtered through rock and soil, but it can be vulnerable to PFAS contamination, nitrates from agriculture, and industrial chemicals that seep into the water table.
About 1% of homes in Twin Falls County, Idaho rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Infrastructure Risk
Detected Contaminants
How City of Twin Falls compares to EPA limits
What This Means For You
Lead at 2 mg/L (action level) exceeds the EPA maximum of 0.015 mg/L (action level). Brain damage in children, kidney & blood pressure in adults. Consider reverse osmosis filtration.
Stage 2 DBP Rule at 2 mg/L exceeds the EPA maximum of mg/L.
Contaminant 1925 at 1 mg/L exceeds the EPA maximum of mg/L.
Contaminant 1996 at 1 mg/L exceeds the EPA maximum of mg/L.
Lead was detected in this water system. reverse osmosis filtration can reduce exposure.
Find a certified water filter →Comparable Water Systems
Similar-sized systems in Idaho
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
City of Twin Falls (EPA ID: ID5420058) is a community water system in Idaho that serves approximately 56,121 people from groundwater sources.
This system provides water to 4 ZIP codes across 3 communities.
Average Home Safety Score: B (71/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| January 1, 2025 | Contaminant 1925 | Monitoring | Unresolved |
| October 17, 2024 | Stage 2 DBP Rule | Health-based | Resolved |
| October 17, 2024 | Stage 2 DBP Rule | Monitoring | Unresolved |
| January 1, 2024 | Contaminant 1996 | Monitoring | Resolved |
| June 18, 2023 | Contaminant 0700 | Monitoring | Resolved |
| January 1, 2023 | Lead | Monitoring | Unresolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Barium | Inorganic | 2 | Yes |
| Lead | Inorganic | 2 | No |
| Stage 2 DBP Rule | Treatment Failure | 2 | Yes |
| Contaminant 1925 | Other Violation | 1 | No |
| Contaminant 1996 | Other Violation | 1 | No |
| Stage 1 DBP Rule | Treatment Failure | 1 | No |
| Contaminant 0700 | Other Violation | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 3 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 1 additional ZIP inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for City of Twin Falls (ID5420058) on EPA.gov.
Frequently Asked Questions
Is City of Twin Falls water safe to drink?
City of Twin Falls has recorded 3 health-based violations in the past 5 years. While the system is required to treat water to meet federal standards, you may want to consider additional precautions such as a certified water filter.
How many people does City of Twin Falls serve?
City of Twin Falls serves approximately 56,121 people across 4 ZIP codes in Idaho.
Where does City of Twin Falls get its water?
The primary water source is groundwater.
Federal UCMR5 PFAS Monitoring: Tested Clean
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were detected.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
How Water Systems Appear in Rankings
Water systems are evaluated by violation history, contaminant detections, and service population. Larger systems with more service connections appear in more rankings.
- #10 / 34 Most Disadvantaged Populations Served (Idaho)
- #12 / 27 Highest Exposure Burden (Idaho)
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
City of Twin Falls (EPA ID: ID5420058) — request the latest Consumer Confidence Report or ask about specific contaminants.