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Tap water quality report

Mason City, IA

EPA monitoring detected 16 contaminants across the 1 water supplier serving Mason City. A detection doesn't automatically mean the water is unsafe — see the level at the main supplier for each below, with its EPA source and period.

1
water supplier
27,338
people served
16
contaminants found
Iowa rankings Lead in Iowa PFAS in Iowa

What was found in Mason City's water

The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.

ContaminantLevel vs EPA limitSuppliersSource
Fluoride
300 µg/L 7.5%
of the EPA limit 4000 µg/L
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2012
1/1 SYR4
Copper
127.15 µg/L 9.8%
of the EPA limit 1300 µg/L
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2017
1/1 SYR4
Lithium
92 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2024
1/1 UCMR-5
Lead
16.9 µg/L 113%
of the EPA limit, at the 95th percentile of samples — 15 µg/L
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2017
1/1 SYR4
Barium
9.4 µg/L 0.5%
of the EPA limit 2000 µg/L
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2012
1/1 SYR4
TTHM
7.292 µg/L 9.1%
of the EPA limit 80 µg/L
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Chloroform
3.145 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Bromodichloromethane
2.75 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Monochloroacetic Acid
2.4 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Combined Radium (-226 And -228)
2.39 pCi/L 48%
of the EPA limit 5 pCi/L
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Dichloroacetic Acid
2.1 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Dibromochloromethane
1.81 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Dibromoacetic Acid
1.294 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Trichloroacetic Acid
1.1855 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Monobromoacetic Acid
1.15 µg/L
No EPA limit set
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2019
1/1 SYR4
Lead
0.0029 mg/L 19%
of the EPA limit 0.0150 mg/L
Main supplier: MASON CITY WATER DEPARTMENT · 27,338 people · 2023
1/1 LCR
Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of the system's samples — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving Mason City

SupplierPopulation served
MASON CITY WATER DEPARTMENT 27,338

Frequently asked questions about Mason City tap water

Is Mason City tap water safe to drink?

EPA testing detected 16 contaminants in the water serving Mason City. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve Mason City?

1 public water supplier report drinking-water monitoring for Mason City, Iowa to the EPA. Each is listed above with its population served.

What contaminants are in Mason City's water?

The contaminants EPA monitoring detected in Mason City include Fluoride, Copper, Lithium, Lead, Barium. The full list, with the level at the main supplier and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.