Storm Lake Drinking Water Meets All Safety Standards in 2025

Storm Lake's drinking water recorded a 90th-percentile lead level of zero parts per billion during 2025 testing, according to the city's annual Consumer Confidence Report released in early April 2026. That figure anchors what the full report documents: a year in which the city's water system logged no violations across every regulated contaminant on its monitoring schedule.

For residents drawing from city taps, zero parts per billion on the lead test means even the highest-sampled homes in the test pool showed no detectable lead coming through the distribution system. The EPA's action level for lead is 15 parts per billion, a threshold that triggers mandatory corrosion-control programs when exceeded at the 90th percentile. Storm Lake wasn't within reach of it.

The city draws its supply from three separate underground sources: the Buried Sand and Gravel aquifer, the Cambrian-Ordovician aquifer, and the Dakota aquifer. State assessments from the Iowa Department of Natural Resources flagged the Buried Sand and Gravel aquifer as the most vulnerable of the three to surface contamination, including agricultural runoff, leaking storage tanks, and chemical spills. The Cambrian-Ordovician and Dakota aquifers sit deeper with natural protective layers overhead, earning lower susceptibility ratings. All three sources go through softening to strip calcium, magnesium, and iron; pH adjustment to reduce pipe corrosion risk; and disinfection with a chlorine solution known as MIOX before entering the distribution system.

Nitrate, a contaminant that demands close attention across Iowa's heavily farmed landscape, came in safely below the EPA maximum contaminant level of 10 milligrams per liter. Copper levels stayed under action thresholds, and the report recorded no violations tied to disinfection byproducts from the chlorination process.

One result the report discloses without triggering alarm: the city participates in the EPA's Unregulated Contaminant Monitoring Rule, a national study tracking substances not yet subject to regulatory limits. Testing under that program detected lithium in Storm Lake's water at concentrations between 110 and 130 parts per billion. Lithium occurs naturally in groundwater and carries no federal maximum contaminant level, but the program requires all participating systems to report any detections. The city's inclusion of those numbers reflects the program's transparency requirement, not an emerging public health concern.

City officials noted their commitment to ongoing treatment improvements, and the 2025 results will serve as a baseline document as Storm Lake advances longer-term infrastructure work, including the recruitment of engineers for a future water-plant upgrade project. The full 2025 Drinking Water Quality Report is available on the city's website, and residents with questions about specific sampling results or treatment practices can reach the water utility directly at 712-291-2680.