Ohio water quality
Ohio has 3,967 active public water systems (16,110 on file total), 1,048 of them graded by TapGraded.
Grade distribution
Biggest water systems
CLEVELAND PUBLIC WATER SYSTEM
CLEVELAND, OH · 1,308,955 served
COLUMBUS PUBLIC WATER SYSTEM
COLUMBUS, OH · 1,305,946 served
CINCINNATI PUBLIC WATER SYSTEM
CINCINNATI, OH · 750,200 served
TOLEDO CITY OF
TOLEDO, OH · 360,000 served
AKRON CITY PWS
KENT, OH · 280,000 served
MONTGOMERY COUNTY WATER SERVICES 1 PWS
KETTERING, OH · 150,207 served
DEL-CO WATER COMPANY, INC.
DELAWARE, OH · 150,000 served
DAYTON PUBLIC WATER SYSTEM
DAYTON, OH · 141,407 served
CLERMONT PUBLIC WATER SYSTEM
BATAVIA, OH · 133,059 served
YOUNGSTOWN CITY PWS
YOUNGSTOWN, OH · 130,530 served
Lowest-graded systems
Active, graded systems serving at least 10,000 people, ordered by lowest Tap Grade first.
VAN WERT CITY
VAN WERT, OH · 10,846 served
MANSFIELD CITY
MANSFIELD, OH · 51,000 served
DAYTON PUBLIC WATER SYSTEM
DAYTON, OH · 141,407 served
DEFIANCE CITY
DEFIANCE, OH · 16,494 served
IRONTON
IRONTON, OH · 11,129 served
GALION CITY
GALION, OH · 10,453 served
AKRON CITY PWS
KENT, OH · 280,000 served
PORTSMOUTH CITY
PORTSMOUTH, OH · 40,475 served
URBANA CITY PWS
URBANA, OH · 11,428 served
BUCKEYE WATER DISTRICT - OHIO RIVER
WELLSVILLE, OH · 10,300 served
Cities in Ohio
Source: EPA SDWIS/ECHO · Data as of 2026Q2