| WASHINGTON SUBURBAN SANITARY COMMISSION | | 1,900,000 | 0.0110 mg/L |
| CITY OF BALTIMORE | | 1,600,000 | 0.0125 mg/L |
| GLEN BURNIE-BROADNECK | | 290,606 | 0.0020 mg/L |
| HOWARD COUNTY D.P.W. DISTRIBUTION | | 286,158 | 0.0124 mg/L |
| HARFORD COUNTY D.P.W. | | 104,567 | 0.0052 mg/L |
| CITY OF HAGERSTOWN | | 92,200 | 0.0054 mg/L |
| NEW DESIGN - FREDERICK COUNTY | | 74,911 | 0.0057 mg/L |
| CROFTON-ODENTON | | 62,986 | 0.0050 mg/L |
| FORT GEORGE G. MEADE | | 62,234 | 0.0076 mg/L |
| CITY OF FREDERICK | | 54,000 | 0.0110 mg/L |
| LEXINGTON PARK | | 43,030 | 0.0036 mg/L |
| CITY OF WESTMINSTER | | 35,256 | 0.0116 mg/L |
| CITY OF ANNAPOLIS | | 35,000 | 0.0000 mg/L |
| CITY OF SALISBURY | | 30,343 | 0.0080 mg/L |
| TOWN OF OCEAN CITY | | 30,000 | 0.0133 mg/L |
| CITY OF CUMBERLAND | | 27,039 | 0.0178 mg/L |
| BROAD CREEK | | 26,033 | 0.0050 mg/L |
| CITY OF BOWIE | | 25,000 | 0.0030 mg/L |
| FREEDOM DISTRICT | | 24,867 | 0.0133 mg/L |
| PATUXENT NAVAL AIR STATION (NAVFAC-WASH) | | 22,000 | 0.0030 mg/L |
| CITY OF ABERDEEN | | 18,006 | 0.0020 mg/L |
| EASTON UTILITIES | | 17,357 | 0.0050 mg/L |
| TOWN OF ELKTON | | 15,625 | 0.0076 mg/L |
| CHAPEL HILL - ABERDEEN PROVING GROUNDS | | 15,000 | 0.0106 mg/L |
| CITY OF CAMBRIDGE WATER | | 15,000 | 0.0057 mg/L |
| CITY OF HAVRE DE GRACE | | 14,000 | 0.0068 mg/L |
| MARYLAND AMERICAN WATER COMPANY | | 13,200 | 0.0126 mg/L |
| OCEAN PINES | | 11,890 | 0.0067 mg/L |
| TOWN OF LA PLATA | | 11,535 | 0.0007 mg/L |
| CITY OF FROSTBURG | | 11,000 | 0.0150 mg/L |
| TOWN OF MOUNT AIRY | | 9,890 | 0.0074 mg/L |
| CHESAPEAKE RANCH ESTATES | | 9,500 | 0.0027 mg/L |
| STEVENSVILLE | | 9,155 | 0.0035 mg/L |
| U.S. NAVAL ACADEMY | | 8,700 | 0.0047 mg/L |
| TOWN OF NORTH EAST | | 8,600 | 0.0126 mg/L |
| TOWN OF WALKERSVILLE | | 8,440 | 0.0100 mg/L |
| FORT DETRICK | | 7,900 | 0.0106 mg/L |
| CITY OF BRUNSWICK | | 7,312 | 0.0000 mg/L |
| CITY OF TANEYTOWN | | 6,750 | 0.0060 mg/L |
| TOWN OF HAMPSTEAD | | 6,600 | 0.0078 mg/L |
| TOWN OF THURMONT | | 6,200 | 0.0184 mg/L |
| TOWN OF POOLESVILLE | | 6,005 | 0.0050 mg/L |
| MYSTIC HARBOUR | | 5,945 | 0.0076 mg/L |
| CITY OF FRUITLAND | | 5,907 | 0.0059 mg/L |
| EASTERN REGION ALLEGANY DISTRIB. SYSTEM | | 5,703 | — |
| LAVALE SANITARY COMMISSION | | 5,500 | 0.0060 mg/L |
| MARYLAND AMERICAN WATER--SEVERN SYSTEM | | 5,447 | 0.0076 mg/L |
| TOWN OF CHESTERTOWN | | 5,400 | 0.0068 mg/L |
| TOWN OF CHESAPEAKE BEACH | | 5,000 | 0.0074 mg/L |
| MIDLAND-LONACONING | | 5,000 | 0.0100 mg/L |
| TOWN OF LEONARDTOWN | | 5,000 | 0.0000 mg/L |
| WESTERN REGION ALLEGANY DISTRIB. SYSTEM | | 4,955 | — |
| TOWN OF MANCHESTER | | 4,954 | 0.0084 mg/L |
| TOWN OF DENTON | | 4,500 | 0.0050 mg/L |
| TOWN OF DELMAR | | 4,500 | 0.0029 mg/L |
| TOWN OF BERLIN | | 4,500 | 0.0100 mg/L |
| TOWN OF PERRYVILLE | | 4,413 | 0.0052 mg/L |
| PRINCE FREDERICK | | 4,371 | 0.0000 mg/L |
| TOWN OF MIDDLETOWN | | 4,288 | 0.0129 mg/L |
| BOONSBORO - KEEDYSVILLE | | 4,250 | 0.0079 mg/L |
| CITY OF POCOMOKE CITY | | 4,100 | 0.0099 mg/L |
| TOWN OF INDIAN HEAD | | 4,100 | 0.0000 mg/L |
| THE PROVINCES | | 3,991 | 0.0000 mg/L |
| SOLOMONS | | 3,811 | 0.0000 mg/L |
| TOWN OF CHARLESTOWN | | 3,791 | 0.0030 mg/L |
| TOWN OF CENTREVILLE | | 3,322 | 0.0096 mg/L |
| NAVAL SUPPORT FACILITY, INDIAN HEAD | | 3,321 | 0.0066 mg/L |
| TOWN OF PRINCESS ANNE | | 3,300 | 0.0054 mg/L |
| COUNTRY LAKES | | 3,016 | 0.0019 mg/L |
| TOWN OF NORTH BEACH | | 3,000 | 0.0050 mg/L |
| TOWN OF MOUNTAIN LAKE PARK | | 3,000 | 0.0038 mg/L |
| CITY OF CRISFIELD | | 2,976 | 0.0037 mg/L |
| TOWN OF EMMITSBURG | | 2,921 | 0.0240 mg/L |
| CEDAR COVE | | 2,728 | 0.0018 mg/L |
| TOWN OF ST. MICHAELS | | 2,650 | 0.0060 mg/L |
| BEL AIR - PINTO DISTRIBUTION SYSTEM | | 2,614 | — |
| FOUNTAINDALE SOUTH | | 2,610 | 0.0059 mg/L |
| TOWN OF SMITHSBURG DISTRIBUTION SYSTEM | | 2,500 | 0.0160 mg/L |
| TOWN OF FEDERALSBURG | | 2,450 | 0.0050 mg/L |
| WAKEFIELD VALLEY | | 2,436 | 0.0073 mg/L |
| TOWN OF SNOW HILL | | 2,409 | 0.0050 mg/L |
| TOWN OF WILLIAMSPORT DISTRIBUTION SYSTEM | | 2,400 | — |
| LAKE VILLAGE TOWNHOMES | | 2,400 | 0.0059 mg/L |
| GREENRIDGE SUBDIVISION | | 2,271 | 0.0063 mg/L |
| HERALD HARBOR | | 2,241 | 0.0050 mg/L |
| TOWN OF RISING SUN | | 2,200 | 0.0108 mg/L |
| TOWN OF WESTERNPORT | | 2,200 | 0.0040 mg/L |
| SAINT MARYS COLLEGE | | 2,200 | 0.0100 mg/L |
| TOWN OF HURLOCK | | 2,150 | 0.0046 mg/L |
| JOHNS HOPKINS UNIVERSITY | | 2,058 | — |
| DELMAR UTILITY COMM (TN OF DELMAR) | DELMAR | 2,027 | 0.0151 mg/L |
| PERRY POINT V.A. MEDICAL CENTER | | 2,000 | 0.0007 mg/L |
| BEACHES WATER CO-OPERATIVE | | 2,000 | 0.0098 mg/L |
| TOWN OF HANCOCK | | 1,921 | 0.0079 mg/L |
| MOUNT SAINT MARYS UNIVERSITY | | 1,900 | 0.0150 mg/L |
| TOWN OF GREENSBORO | | 1,878 | 0.0030 mg/L |
| TOWN OF OAKLAND | | 1,850 | 0.0038 mg/L |
| POTOMAC HEIGHTS | | 1,800 | 0.0000 mg/L |
| SWANN KEYS | FENWICK ISLAND | 1,764 | 0.0039 mg/L |
| TOWN OF ROCK HALL | | 1,750 | 0.0058 mg/L |