A92/100
JOHNSTON MUNICIPAL WATER SUPPLY — Water Quality Report 2026
Serving 24,064 people · Iowa
Water Source
Purchased Surface Water
County
—
System ID
IA7740011
Violations
4
Contaminant Test Results
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2013.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Frequently Asked Questions About JOHNSTON MUNICIPAL WATER SUPPLY
Is JOHNSTON MUNICIPAL WATER SUPPLY water safe to drink?
JOHNSTON MUNICIPAL WATER SUPPLY water receives a grade of A (92/100), which is considered excellent. Out of 69 contaminants tested, none exceed EPA legal limits. The water meets federal safety standards.
What contaminants has JOHNSTON MUNICIPAL WATER SUPPLY detected?
69 contaminants were tested in JOHNSTON MUNICIPAL WATER SUPPLY's water. No contaminants exceed EPA legal limits or health goals, indicating good water quality management.
Does JOHNSTON MUNICIPAL WATER SUPPLY have any EPA violations?
Yes, JOHNSTON MUNICIPAL WATER SUPPLY has 4 EPA violation(s) on record, with the most recent in 2013. Violation types include MCL, MR. 1 are health-based violations.
How many people does JOHNSTON MUNICIPAL WATER SUPPLY serve?
JOHNSTON MUNICIPAL WATER SUPPLY serves approximately 24,064 people, Iowa. The system provides water to 1 community: Johnston.
What type of water does JOHNSTON MUNICIPAL WATER SUPPLY provide?
JOHNSTON MUNICIPAL WATER SUPPLY sources its water from purchased surface water. Surface water comes from rivers, lakes, or reservoirs and typically requires more extensive treatment. The utility's system ID is IA7740011.
How does JOHNSTON MUNICIPAL WATER SUPPLY compare to other utilities in Iowa?
JOHNSTON MUNICIPAL WATER SUPPLY scores 92/100 with a grade of A (excellent). This places it among the higher-performing utilities in the state. Visit our Iowa state page for a full comparison of water systems.