Water Quality in MASON CITY, IA (50401)

EPA violation data for public water systems serving ZIP code 50401.

Total Violations

Health-Based

Monitoring / Reporting

Resolved

What does this mean?

71 of 71 violations have been resolved. 22 are health-based violations, meaning contaminant levels exceeded federal safety limits. The remaining 49 are monitoring or reporting violations (missed testing deadlines or late paperwork — not necessarily a water quality issue). Not all violations mean your water is unsafe. The EPA requires reporting even for minor administrative issues.

Water systems: 39 Population served: 29,049

Violations Detail (71 total)

Contaminant	Category	MCL Limit	Measured	Date	Status	Health Effects
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jul 31, 2025	Resolved	N/A
Nitrate	Monitoring	N/A	N/A	Jul 31, 2025	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Jul 31, 2025	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Jul 31, 2025	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jul 31, 2025	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Jul 31, 2025	Resolved	N/A
Nitrate	Health-Based	N/A	13.5	Sep 30, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	13.5	Sep 30, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	13.5	Sep 30, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	13.5	Sep 30, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	11.759	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrite	Health-Based	N/A	1.0945	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrite	Health-Based	N/A	1.0945	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrite	Health-Based	N/A	1.0945	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrite	Health-Based	N/A	1.0945	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	11.759	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	11.759	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	11.759	Aug 31, 2024	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2024	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	May 31, 2024	Resolved	N/A
Nitrate	Health-Based	N/A	16.7	Sep 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	16.7	Sep 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	16.7	Sep 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	16.7	Sep 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	N/A
Nitrate	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Aug 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	14.8	Jul 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	14.8	Jul 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	14.8	Jul 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Health-Based	N/A	14.8	Jul 31, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	N/A
Nitrate	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Apr 30, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Feb 28, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Feb 28, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Feb 28, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Feb 28, 2023	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Sep 30, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Sep 30, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Sep 30, 2022	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Sep 30, 2022	Resolved	N/A
Revised Total Coliform Rule	Health-Based	N/A	N/A	Mar 31, 2022	Resolved	N/A
Revised Total Coliform Rule	Health-Based	N/A	N/A	Mar 31, 2022	Resolved	N/A
Nitrate	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Nitrate	Monitoring	N/A	N/A	Sep 30, 2021	Resolved	Infants below the age of six months could become seriously ill (blue baby syndrome); shortness of breath
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A
Revised Total Coliform Rule	Monitoring	N/A	N/A	Aug 31, 2021	Resolved	N/A

Lead & Copper Levels

Violation Timeline

2025(6)

Revised Total Coliform Rule

Jul 31Resolved

Nitrate

Jul 31Resolved

Nitrate

Jul 31Resolved

Nitrate

Jul 31Resolved

Revised Total Coliform Rule

Jul 31Resolved

Revised Total Coliform Rule

Jul 31Resolved

2024(16)

Nitrate

Sep 30Resolved

Nitrate

Sep 30Resolved

Nitrate

Sep 30Resolved

Nitrate

Sep 30Resolved

Nitrate

Aug 31Resolved

Nitrite

Aug 31Resolved

Nitrite

Aug 31Resolved

Nitrite

Aug 31Resolved

Nitrite

Aug 31Resolved

Nitrate

Aug 31Resolved

Nitrate

Aug 31Resolved

Nitrate

Aug 31Resolved

Revised Total Coliform Rule

May 31Resolved

Revised Total Coliform Rule

May 31Resolved

Revised Total Coliform Rule

May 31Resolved

Revised Total Coliform Rule

May 31Resolved

How Does This Compare?

MASON CITY (50401) has 71 recorded violations, including 22 health-based. All violations have been resolved, which is a positive sign for current water quality. Consider testing your tap water independently for added peace of mind.

Recommended Water Filters

Based on the contaminants detected in your area, these filter types may help improve your water quality.

Reverse Osmosis System

One of the few filtration methods effective at removing nitrates and nitrites. Essential for households with infants.

Targets:Nitrate, Nitrite, Dissolved Solids

Look for:NSF/ANSI 58 certified

NSF Certified Products → EPA Safe Drinking Water Guide →

UV Water Purifier

Uses ultraviolet light to neutralize bacteria, viruses, and parasites without chemicals. Ideal for homes with microbial contamination concerns.

Targets:E. coli, Coliform, Giardia, Cryptosporidium

Look for:NSF/ANSI 55 (Class A) certified

NSF Certified Products → EPA Safe Drinking Water Guide →

Always look for filters certified by NSF International for the specific contaminants you want to remove.

Water Quality in MASON CITY, IA (50401)

What does this mean?

Violations Detail (71 total)

Lead & Copper Levels

Violation Timeline

2025(6)

2024(16)

2023(29)

2022(6)

2021(14)

How Does This Compare?

Recommended Water Filters

Reverse Osmosis System

UV Water Purifier

Nearby ZIP Codes

Check Another ZIP Code