Large Systems (100K+)
Major metropolitan water systems serving over 100,000 people.
Grade Distribution
Large Systems (100K+) (162)
Chicago
Chicago, Illinois
San Antonio Water System
San Antonio, Texas
Washington Suburban Sanitary Commission
Laurel, Maryland
Phoenix City Of
Phoenix, Arizona
Philadelphia Water Department
Philadelphia, Pennsylvania
City of Baltimore
Baltimore, Maryland
Las Vegas Valley Water District
Las Vegas, Nevada
East Bay MUD
Oakland, California
Dallas Water Utility
Dallas, Texas
Cleveland Public Water System
Cleveland, Ohio
Columbus Public Water System
Columbus, Ohio
Denver Water Board
Denver, Colorado
Charlotte Water
Charlotte, North Carolina
Fairfax County Water Authority
Herndon, Virginia
Mo American St Louis St Charles Counties
Chesterfield, Missouri
Atlanta
Atlanta, Georgia
Gwinnett Co. Dept. of Water Resources
Lawrenceville, Georgia
Citizens Water - Indianapolis
Indianapolis, Indiana
Jea Major Grid
Jacksonville, Florida
Aqua Pa Main System
Bryn Mawr, Pennsylvania
Veolia Water New Jersey Hackensack
Haworth, New Jersey
Metro Water Services
Nashville, Tennessee
Louisville Water Company
Louisville, Kentucky
Cincinnati Public Water System
Cincinnati, Ohio
Dekalb County
Decatur, Georgia
Tucson City Of
Tucson, Arizona
Cobb County
Marietta, Georgia
Boston Water and Sewer Commission (mwra)
Boston, Massachusetts
Portland Water Bureau
Portland, Oregon
Metropolitan Utilities District
Omaha, Nebraska
Memphis Light, Gas, & Water
Memphis, Tennessee
Oklahoma City
Oklahoma City, Oklahoma
Raleigh, City Of
Raleigh, North Carolina
Detroit City Of
Detroit, Michigan
Milwaukee Waterworks
Milwaukee, Wisconsin
Baton Rouge Water Company
Baton Rouge, Louisiana
Central Alabama Water System
Birmingham, Alabama
Albuquerque Water System
Albuquerque, New Mexico
City of Fresno
Fresno, California
Aurora City Of
Aurora, Colorado
Kansas City Pws
Kansas City, Missouri
Mcwa
Rochester, New York
Water District 1 of Johnson Co
Kansas City, Kansas
Mesa City Of
Mesa, Arizona
Colorado Springs Utilities
Colorado Springs, Colorado
Truckee Meadows Water Authority
Reno, Nevada
Virginia Beach, City Of
Virginia Beach, Virginia
North Fulton County
Alpharetta, Georgia
Minneapolis
Minneapolis, Minnesota
Regional Water Authority
New Haven, Connecticut
Tulsa
Tulsa, Oklahoma
Newport News, City Of
Newport News, Virginia
Greenville Water (2310001)
Greenville, South Carolina
Wichita, City Of
Wichita, Kansas
Saint Paul Regional Water Services
St. Paul, Minnesota
Metropolitan District Commission
Hartford, Connecticut
Chesterfield Co Central Water System
Chesterfield, Virginia
Winston-Salem, City Of
Pfafftown, North Carolina
Salt Lake City Water System
Salt Lake City, Utah
North Las Vegas Utilities
North Las Vegas, Nevada
Central Arkansas Water
Little Rock, Arkansas
Aquarion-Eastern Fairfield County
Shelton, Connecticut
Alameda County Water District
Fremont, California
Henderson City Of
Henderson, Nevada
Ecwa Direct
Buffalo, New York
New Orleans Carrollton Water Works
New Orleans, Louisiana
Loudoun Water - Central System
Ashburn, Virginia
Charleston Water System (sc1010001)
Charleston, South Carolina
Durham, City Of
Durham, North Carolina
Greensboro, City Of
Greensboro, North Carolina
Columbia City of (sc4010001)
Columbia, South Carolina
Bellevue City Of
Bellevue, Washington
St Louis City Pws
St Louis, Missouri
Kentucky-American Water Co
Lexington, Kentucky
Lincoln, City Of
Lincoln, Nebraska
Newark Water Department
Newark, New Jersey
Cocoa, City Of
Cocoa, Florida
City of Plano
Plano, Texas
Glen Burnie-Broadneck
Millersville, Maryland
Howard County D.p.w. Distribution
Columbia, Maryland
Mobile, Bd. Of W&s Comm. Of the City Of
Mobile, Alabama
Buffalo Water Authority
Buffalo, New York
Montgomery (ww&ssb of the City Of)
Montgomery, Alabama
E Jefferson Ww District 1
Jefferson, Louisiana
Grand Rapids
Grand Rapids, Michigan
Madison Water Utility
Madison, Wisconsin
Fort Wayne - 3 Rivers Filtration Plant
Fort Wayne, Indiana
CWS - Bakersfield
San Jose, California
Nj American Water - Western
Delran, New Jersey
Huntsville Utilities
Huntsville, Alabama
Jersey City Mua
Hoboken, New Jersey
Knoxville Utilities Board - Kub
Knoxville, Tennessee
Clarksville Water Department
Clarksville, Tennessee
City of Garland
Garland, Texas
Gilbert, Town Of
Gilbert, Arizona
Gsw&sa (sc2620004)
Conway, South Carolina
Chandler City Of
Chandler, Arizona
Des Moines Water Works
Des Moines, Iowa
Emerald Coast Utilities Authority (ecua)
Pensacola, Florida
Ann Arbor
Ann Arbor, Michigan
City of Frisco
Frisco, Texas
Thornton City Of
Thornton, Colorado
Tualatin Valley Water District
Beaverton, Oregon
Liberty Utilities New York - Lynbrook
Merrick, New York
Wildwood City Water Department
Rio Grande, New Jersey
Everett Public Works Dept. City Of
Everett, Washington
Rochester City
Rochester, New York
Tennessee American Water
Chattanooga, Tennessee
Springfield Pws
Springfield, Missouri
Indiana American Water - Northwest
Greenwood, Indiana
Wvawc-Kanawha Valley Dist
Charleston, West Virginia
Worcester Dpwp, Water Supply Division
Worcester, Massachusetts
Westminster City Of
Westminster, Colorado
Tallahassee, City Of
Tallahassee, Florida
Alderwood Water District
Lynnwood, Washington
Salem Public Works
Salem, Oregon
Northern Kentucky Water District
Ft. Thomas, Kentucky
Contra Costa Water District
Concord, California
Gru - Murphree Wtp
Gainesville, Florida
Kalamazoo
Kalamazoo, Michigan
Shreveport Water System
Shreveport, Louisiana
City of Jackson
Jackson, Mississippi
Aurora
Aurora, Illinois
Evansville Water Utility
Evansville, Indiana
Eugene Water & Electric Board
Eugene, Oregon
Lafayette Utilities Water System
Lafayette, Louisiana
Springfield Water and Sewer Commission
Springfield, Massachusetts
Tuscaloosa Water & Sewer
Tuscaloosa, Alabama
Kent Water Department
Kent, Washington
Lansing Board of Water & Light
Lansing, Michigan
Redmond Water System City Of
Redmond, Washington
Naperville
Naperville, Illinois
Kansas City Board of Public Utilities
Kansas City, Kansas
Del-Co Water Company, INC.
Delaware, Ohio
Il American-Champaign
Godfrey, Illinois
Iowa-American Wtr Co-Davenport
Davenport, Iowa
Bjw&sa (0720003)
Okatie, South Carolina
Olathe, City Of
Olathe, Kansas
Cedar Rapids Water Department
Cedar Rapids, Iowa
Chester Water Authority
Chester, Pennsylvania
Pa Amer Water Co Lake Scranton
Wilkes Barre, Pennsylvania
Clermont Public Water System
Batavia, Ohio
City of Columbia Utilities
Columbia, Missouri
Topeka, City Of
Topeka, Kansas
Rochester
Rochester, Minnesota
Granger-Hunter Improvement District
Salt Lake City, Utah
Aquarion-Stamford
Shelton, Connecticut
Cambridge Water Department
Cambridge, Massachusetts
West Jordan City Water System
West Jordan, Utah
Fayetteville Waterworks
Fayetteville, Arkansas
Broken Arrow Municipal Authority
Broken Arrow, Oklahoma
Provo City
Provo, Utah
Lowell Regional Water Utility
Lowell, Massachusetts
South Bend Water Works
South Bend, Indiana
Green Bay Waterworks
Green Bay, Wisconsin
Rio Rancho Water & Ww Services
Rio Rancho, New Mexico
Waterbury Water Department
Waterbury, Connecticut
Medford Water Commission
Medford, Oregon
St George City Water System
St George City, Utah
Racine Waterworks
Racine, Wisconsin
Norman Utilities Authority
Norman, Oklahoma
Harford County D.p.w.
Abingdon, Maryland
Frequently Asked Questions
Large Systems (100K+) have an average Water Safety Score of 81/100. 35 of 162 systems (22%) have at least one health-based violation. Large systems generally have better resources for treatment and monitoring.
162 large systems (100k+) collectively serve 71,240,969 people. Large systems serve the majority of the US population despite being fewer in number.
System size can influence water quality. Larger systems typically have more resources for water treatment, testing, and infrastructure maintenance. Smaller systems may struggle with compliance due to limited budgets and staff. However, size alone does not determine water quality — source water quality, treatment methods, and infrastructure age all play roles.