Iowa water quality
Iowa has 1,821 active public water systems (5,293 on file total), 1,078 of them graded by TapGraded.
Grade distribution
Biggest water systems
DES MOINES WATER WORKS
DES MOINES, IA · 246,055 served
IOWA-AMERICAN WTR CO-DAVENPORT
DAVENPORT, IA · 147,720 served
CEDAR RAPIDS WATER DEPARTMENT
CEDAR RAPIDS, IA · 142,364 served
SIOUX CITY WATER SUPPLY
SIOUX CITY, IA · 85,791 served
ANKENY, CITY OF
ANKENY, IA · 76,207 served
WEST DES MOINES WATER WORKS
WEST DES MOINES, IA · 73,959 served
WATERLOO WATER WORKS
WATERLOO, IA · 69,504 served
IOWA CITY WATER DEPARTMENT
IOWA CITY, IA · 68,753 served
COUNCIL BLUFFS WATER WORKS
COUNCIL BLUFFS, IA · 64,447 served
DUBUQUE WATER WORKS
DUBUQUE, IA · 59,667 served
Lowest-graded systems
Active, graded systems serving at least 10,000 people, ordered by lowest Tap Grade first.
WAVERLY WATER DEPARTMENT
WAVERLY, IA · 10,394 served
DUBUQUE WATER WORKS
DUBUQUE, IA · 59,667 served
SIOUX CITY WATER SUPPLY
SIOUX CITY, IA · 85,791 served
IOWA-AMERICAN WTR CO-DAVENPORT
DAVENPORT, IA · 147,720 served
WATERLOO WATER WORKS
WATERLOO, IA · 69,504 served
MUSCATINE POWER & WATER
MUSCATINE, IA · 25,516 served
ALTOONA WATER SUPPLY
ALTOONA, IA · 19,565 served
BOONE WATER WORKS
BOONE, IA · 12,704 served
MARION MUNICIPAL WATER DEPT
MARION, IA · 41,623 served
OTTUMWA WATER WORKS
OTTUMWA, IA · 25,529 served
Cities in Iowa
Source: EPA SDWIS/ECHO · Data as of 2026Q2