Johnston Municipal Water Supply
EPA ID: IA7740011 · 24,064 people served · 4 ZIP codes
Based on the latest federal compliance data, Johnston Municipal Water Supply has 3 violations that the EPA has not yet closed — those outstanding findings are part of the enforcement record for a utility that delivers water to approximately 24,064 people throughout its service territory.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Johnston Municipal Water Supply Source: EPA SDWIS service area boundaries.
Service area boundary — Grade C
Service Area Demographics
The Johnston Municipal Water Supply serves a community with a median household income of $105,834 and an estimated 75,707 residents across its service area.
🌊 Where Does Your Water Come From?
Johnston Municipal Water Supply's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in Polk County, Iowa rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Detected Contaminants
How Johnston Municipal Water Supply compares to EPA limits
What This Means For You
Contaminant 1003 at 1 mg/L exceeds the EPA maximum of mg/L.
Contaminant 1032 at 1 mg/L exceeds the EPA maximum of mg/L.
Contaminant 1052 at 1 mg/L exceeds the EPA maximum of mg/L.
Comparable Water Systems
Similar-sized systems in Iowa
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
Johnston Municipal Water Supply (EPA ID: IA7740011) is a community water system in Iowa that serves approximately 24,064 people from surface water sources.
This system provides water to 4 ZIP codes across 4 communities.
Average Home Safety Score: C (59/100)
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 |
|---|---|---|---|
| October 1, 2024 | Contaminant 1003 | Monitoring | Unresolved |
| July 1, 2024 | Contaminant 1032 | Monitoring | Unresolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Contaminant 1003 | Other Violation | 1 | No |
| Contaminant 1032 | Other Violation | 1 | No |
| Contaminant 1052 | Other Violation | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
| ZIP Code | Lead Level | Exceeds Limit | Sample Date |
|---|---|---|---|
| 50131 | 0.0016 mg/L | No | N/A |
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 1 (High 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: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by IA or modeled from parcel and building-footprint data.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Johnston Municipal Water Supply (IA7740011) on EPA.gov.
Frequently Asked Questions
Is Johnston Municipal Water Supply water safe to drink?
Johnston Municipal Water Supply has only monitoring/reporting violations, which are procedural in nature. The system meets federal health-based standards.
How many people does Johnston Municipal Water Supply serve?
Johnston Municipal Water Supply serves approximately 24,064 people across 4 ZIP codes in Iowa.
Where does Johnston Municipal Water Supply get its water?
The primary water source is surface water.
Contact Your Water Utility
Public-record contact information for the water utility serving this system. Use these channels to request water quality reports, ask about service, or report issues directly.
Contact information from Johnston Municipal Water Supply Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility, does not act as its agent, and does not provide customer support for it. Contact details shown are public-record information from CCR filings. For service issues, contact the utility directly using the information above.
Water Source & Treatment
Where this water originates and how it's treated before reaching your tap.
Source: Johnston Municipal Water Supply Consumer Confidence Report.
ZipCheckup is not affiliated with this water utility. Treatment and source data are sourced from the utility's published CCR filings.
Surface water sources are highly susceptible to contamination. The Alluvial Aquifer is highly susceptible. The Cambrian-Ordovician Aquifer has low susceptibility.
Treatment regime
How this utility classifies its treatment process and what each reported treatment chemical does.
Treatment chemicals and what each one does
Chemical names are reported verbatim by the utility. Purpose categories are ZipCheckup annotations based on standard drinking-water treatment practice.
Watershed exposure sources reported
Land-use and natural conditions identified in the utility's source-water assessment as potential contamination sources upstream of treatment.
Treatment classification and chemical list sourced from Johnston Municipal Water Supply Consumer Confidence Report.
Treatment intensity is a ZipCheckup-derived classification based on the chemicals and processes the utility reports. Chemicals and contamination sources are taken verbatim from the utility's CCR filing. Routine federal monitoring and contaminant testing shown elsewhere on this page determine whether the water meets safety standards, not the treatment classification.
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.
Notable events and violations
This section summarizes events the utility chose to disclose in its most recent Consumer Confidence Report, plus any federal compliance violations the utility recorded against itself. Both lists are utility-authored — ZipCheckup does not audit, judge, or reorder them.
Notable events from the utility's CCR
These bullet entries are the utility's own narration of operational, regulatory, or infrastructure events during the reporting period.
- Regional CCR: Johnston Municipal Water Supply is served by Des Moines Water Works. Distribution-level monitoring data specific to Johnston: lead ND, copper 0.117 ppm, 20 coliform samples with 1 positive (no violation — repeat samples negative).
- No violations for Johnston service area.
ZipCheckup note: items above reflect what the utility published in its most recent CCR. Federal violation records are also tracked separately by the EPA Safe Drinking Water Information System (SDWIS) — the SDWIS record is the authoritative federal source for any specific regulatory action.
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
Johnston Municipal Water Supply (EPA ID: IA7740011) — request the latest Consumer Confidence Report or ask about specific contaminants.