Twin Knolls Fourth/fifth Addition
EPA ID: IA5784326 · 90 people served · 2 ZIP codes
Throughout five consecutive years of federal water monitoring, Twin Knolls Fourth/fifth Addition recorded zero violations — solid performance for a utility serving 90 people.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Twin Knolls Fourth/fifth Addition Source: EPA SDWIS service area boundaries.
Service area boundary
Service Area Demographics
The Twin Knolls Fourth/fifth Addition serves a community with a median household income of $122,213 and an estimated 9,729 residents across its service area. Approximately 41% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
Twin Knolls Fourth/fifth Addition'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 Linn 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 80th percentile nationally for proximity to Superfund (NPL) sites. Groundwater sources near contaminated sites may face elevated risk from industrial chemicals.
Infrastructure Risk
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
Twin Knolls Fourth/fifth Addition (EPA ID: IA5784326) is a community water system in Iowa that serves approximately 90 people from groundwater sources.
This system provides water to 2 ZIP codes across 2 communities.
Violation History
Lead & Copper
No Lead and Copper Rule sampling data available for this water system.
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: 1 ZIP code 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 Twin Knolls Fourth/fifth Addition (IA5784326) on EPA.gov.
Frequently Asked Questions
Is Twin Knolls Fourth/fifth Addition water safe to drink?
Based on EPA records, Twin Knolls Fourth/fifth Addition has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does Twin Knolls Fourth/fifth Addition serve?
Twin Knolls Fourth/fifth Addition serves approximately 90 people across 2 ZIP codes in Iowa.
Where does Twin Knolls Fourth/fifth Addition get its water?
The primary water source is groundwater.
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.