Is Marengo, IA Tap Water Safe to Drink?
Graded B-, with 4 unresolved violations on record. See what was cited — and what it means for your tap. What to do next ↓
71.1/100
waterverge.com Marengo, IA — Water Quality Report
Marengo's drinking water received a grade of B- (71.1 out of 100), indicating fair water quality. The city's 2 water systems serve approximately 2,481 residents using groundwater.
Lead levels were measured at 6.0 ppb (90th percentile), which is within EPA limits but above recommended levels. This system has not yet been tested for PFAS under the EPA UCMR 5 program.
The system has 55 violations on record, including 12 health-based violations. 4 remain unresolved.
What to know about Marengo's water
Marengo ranks #419 out of 436 cities in Iowa for water quality, placing it among the lowest-rated in the state.
Marengo 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.
While lead levels are within EPA limits, they are above the recommended 5 ppb threshold that health organizations consider ideal. A point-of-use filter adds an extra layer of protection.
As a small community water system, Marengo may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 9 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Marengo, IA water safe to drink?
Marengo's drinking water has significant quality concerns based on EPA testing data. With a grade of B- (71.1/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 2 water systems serve approximately 2,481 residents using groundwater (wells).
Recent water quality updates for Marengo
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Marengo's water quality assessment. Grade: B- (71.1/100).
1 health-based. Contaminants: Nitrate.
1 health-based. Contaminants: Nitrate.
1 health-based. Contaminants: Nitrate.
Federal disaster declaration (FEMA DR-4430). Flood event — may have impacted local water infrastructure.
Federal disaster declaration (FEMA DR-4421). Flood event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Marengo's water supply.
Within EPA limits but above the American Academy of Pediatrics recommended level of 1 ppb. An NSF 53-certified filter provides additional protection.
Violation history
Marengo's water system has 55 total violations on record, including 12 health-based violations. 4 remain unresolved. 9 violations were issued in the last 5 years.
Flood & environmental risk
Iowa County has experienced 10 federally declared disasters since 1974. 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 Bear Creek At Ladora, Iowa River At Marengo.
Where does Marengo's water come from?
Marengo's drinking water comes from groundwater (wells), supplied by 2 water systems serving approximately 2,481 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 Bear Creek At Ladora (river), Iowa River At Marengo (river).
What Marengo residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Marengo'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.
Marengo's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Marengo
Industrial polluters nearby
Reported releases to surface water by facilities near Marengo, ranked by pounds discharged annually.
Total reported releases to surface water: 21,001 lbs
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
WHIRLPOOL CORP AMANA, IA52203 | Nitrate compounds (water dissociable; reportable only when in aqueous solution) | 21,000 | 8.9 mi |
WILLIAMSBURG MANUFACTURING WILLIAMSBURG, IA52361 | Lead | 1 | 9.9 mi |
KINZE MANUFACTURING INC WILLIAMSBURG, IA52361 | — | — | 7.2 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Flood & disaster history
Iowa County has experienced 10 federally declared disasters since 1974. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Marengo's water supply, we recommend the following filter types.
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. | 6.0 | 15 | ppb | Inorganic | Safe |
Lead level trend (90th percentile)
See how Marengo compares by contaminant
Explore where Marengo ranks among all Iowa cities for specific contaminants.
Water source & infrastructure
Where Marengo's water comes from
Marengo'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 2,481 people through 2 water systems.
Water bodies near Marengo
Marengo is located near 2 notable water bodies. These water bodies contribute to the regional watershed and may indirectly affect groundwater quality.
Water systems serving Marengo
| System Name | PWSID | Population | Source |
|---|---|---|---|
| MARENGO WATER SUPPLY | IA4843033 | 2,435 | GW |
| IOWA VALLEY ESTATES | IA4800634 | 46 | GW |
How Marengo compares
Full Iowa rankings →Marengo's score of 71.1/100 is on par with the average of 72/100 among major Iowa cities. It outscores 3 of 10 nearby cities. 7 of 10 nearby cities score higher.
Nearby cities
View Iowa rankings →About Marengo, IA
Learn more about your water
Guides and resources related to Marengo's water quality findings.
Explore water quality across Iowa
Frequently asked questions
Is Marengo, IA tap water safe to drink?
Marengo's water quality earned a grade of B- (71.1/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #419 out of 436 cities tested in Iowa.
What contaminants are in Marengo's water?
Lead was measured at 6.0 ppb (90th percentile). 55 violations are on record.
How is Marengo'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 Marengo?
While lead levels are within EPA limits, a filter adds extra protection. Based on current data, basic filtration should suffice for additional peace of mind.
Where does Marengo's water come from?
Marengo's water is sourced from Groundwater. The city has 2 water systems serving approximately 2,481 residents.
What health violations has Marengo's water system had?
Marengo has 12 health-based violations on record. The most recent violation was recorded in October 2023. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 4 violations remain unresolved.
Is Marengo's groundwater at risk of contamination?
Marengo 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 55 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 Marengo's water compare to other cities?
Marengo ranks #419 out of 436 cities in Iowa (better than 4% of state cities) and #10616 out of 15744 cities nationally (33th percentile). The grade of B- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.