Iowa Water Quality Rankings 2026: Best & Worst Cities

This page ranks the 24 Iowa cities whose water systems we have matched to EPA records. Every city starts at 100 points and loses points for health-based EPA violations in the last five years (SDWIS 2026Q2), its most recent Lead and Copper Rule 90th-percentile result, PFAS detected in EPA's 2023–2026 UCMR5 monitoring, and 2012–2019 compliance samples that averaged near or above a limit. Letters follow fixed bands (A ≥90, B ≥80, C ≥70, D ≥60, F below 60). Cities run from the highest score (Des Moines) down to the lowest (Sioux City); ties are ordered by population served. See the full scoring methodology for every deduction and the data vintages. 1 further Iowa city is listed at the bottom without a grade because we have not yet matched it to an EPA water system.

What your city's grade means

An A or B grade points to water that consistently tests within federal safety limits, while a C suggests moderate issues worth watching and a D or F flags contaminants or compliance problems serious enough to act on. These grades describe system-level water leaving the treatment plant — they can't account for your home's own plumbing, so older houses with lead service lines or fixtures can add contaminants after the water arrives. For a contaminant-by-contaminant view, see the Iowa contaminant breakdown or drill into the county-level rankings.

What Iowa residents should do

• Find your city in the ranking below and open its full report for its violation history, lead results and PFAS table.
• See how Iowa compares against the best-rated and worst-rated cities nationwide.
• Test your home's water if you have concerns — the most common issues involve lead, PFAS, and arsenic.
• Check whether your utility still has lead service lines in Iowa — EPA's inventory counts lead pipes by water system, a risk that plant-level grades cannot capture. Read the lead guide for testing and filter options.
• If treatment makes sense for your situation, compare certified water filters matched to the contaminants found in your area.

We track 25 cities in Iowa. 24 of them are matched to an active EPA-registered community water system (PWSID). Those 24 systems report serving 1,470,797 people in EPA's Safe Drinking Water Information System (SDWIS).

Of 24 cities of the 25 Iowa cities we can grade from EPA records, 22 cities (92%) grade B or better, 2 sit in the C range and 0 grade D or F. The average score is 96/100. 1 city is not graded because it has not been matched to an EPA system yet.

None of the 24 graded systems has a health-based EPA violation in the last five years; the 8 violations on file in that window are monitoring or reporting lapses.

24 cities have a Lead and Copper Rule 90th-percentile result from 2020 or later: 2 cities at 5 ppb or more.

EPA's UCMR5 PFAS monitoring (2023–2026) covers 24 cities: PFAS were detected in 7 cities, and PFOA or PFOS reached EPA's 4 ppt limit in 4 cities.

Ankeny scores highest (100) and Sioux City lowest (72), a 28-point spread.

Lead pipes are the part of tap-water risk a treatment-plant grade cannot see, so start with EPA's service line inventory (Q2 2026 snapshot). 1,194 Iowa systems inventoried 1,186,924 service lines: 55,535 confirmed lead plus 12,510 galvanized lines requiring replacement, spread across 294 systems. Another 180,543 lines (15%) are still of unknown material, which EPA counts as possible lead until verified.

Of the 24 city-linked Iowa utilities with an inventory on file, 17 report at least one lead or galvanized-requiring-replacement line and 7 report no lead with most lines verified. DES MOINES WATER WORKS, which serves Des Moines and 246,055 people, is the biggest and reports 8,114 lead lines and 10 galvanized requiring replacement. The most lead lines among city-linked systems belong to IOWA-AMERICAN WTR CO-DAVENPORT (Davenport): 9,620.

Iowa's guide on this site singles out nitrates, atrazine and other herbicides, bacteria, and arsenic. Nitrate (EPA MCL 10 mg/L (as nitrogen)) can cause methemoglobinemia ("blue baby syndrome") in infants under six months; Atrazine (EPA MCL 0.003 mg/L) is associated with cardiovascular and reproductive effects; Coliform bacteria (any E. coli-positive sample violates the Revised Total Coliform Rule) signal that disease-causing organisms may be present; Arsenic (EPA MCL 0.010 mg/L (10 ppb)) is linked to skin damage, circulatory problems and increased cancer risk.

Where a system draws its water shapes which of these show up. Disinfection byproducts are a surface-water signature: chlorine reacts with organic matter in rivers and reservoirs, so byproducts tend to run higher where systems chlorinate surface water. Arsenic is naturally occurring and tends to show up in groundwater, leaching from bedrock into aquifers rather than arriving from pollution. Nitrate and atrazine follow fertilizer, manure and septic loading, so they are most often a concern for systems drawing shallow groundwater in farm regions. Lead is different again: it enters after treatment from service lines and household plumbing, which is why the inventory figures above matter more than plant-level results. Your utility's Consumer Confidence Report names your source.

The best water quality in Iowa is found in Des Moines with a score of 100/100 and a grade of A. This puts Des Moines among the top-performing cities in the country for drinking water safety.

The most concerning water quality is in Sioux City scoring 72/100 with a grade of C. Residents may want to consider home water testing and filtration options.

The statewide average score is 96/100, which is 8 points above the national average of 88/100. A strong majority (83%) of Iowa cities exceed the national average, indicating generally good water infrastructure across the state.