Johnston Tap Water Quality: Is It Safe to Drink? (2026 Report)

Johnston, Iowa tap water receives a grade of B (61/100), which is considered good. Out of 70 contaminants tested, 1 exceed EPA maximum contaminant levels (MCLs) and 2 exceed health guidelines (MCLGs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.

Of the 70 contaminants tested in Johnston's water supply, the most notable include Copper (90th percentile), Lead (90th percentile). 1 contaminant(s) exceed EPA legal limits (MCLs). 2 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.

Yes, Johnston has 43 EPA violation(s) on record, with the most recent in 2024. Violation types include MR, MCL. 6 of these are health-based violations, which are the most serious category.

Based on EPA data, using a water filter in Johnston is recommended. 1 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.

Johnston's drinking water is sourced from groundwater and supplied by CAMP DODGE WATER SUPPLY and 1 other water system(s). The system serves approximately 25,233 people. Groundwater is pumped from underground aquifers, which often provides natural filtration.

Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Johnston's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.

Johnston's water quality score of 61/100 earns a grade of B, which is considered good. This is an above-average score compared to many cities nationwide. Visit our Iowa state page to see how all cities in the state compare.

If you have concerns about Johnston's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (CAMP DODGE WATER SUPPLY) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.