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Getting your well water tested in Illinois

Use a lab Illinois certifies, or a mail-in kit. Across the state, the ones worth testing for are nitrate, arsenic and manganese, plus bacteria every year.

Compare lab tests Find my county

About 1,227,000 people in Illinois get their water from a private well, about 1 in 10 residents.

Three ways to get tested, cheapest first.

2

A lab Illinois certifies

The state's list of labs certified for drinking water. Many sell bottles you pick up or get by mail, and their results count for a home sale or loan.

Labs certified by Illinois
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A mail-in kit

Order online, fill the bottles at your kitchen tap and get results by email in about a week. Full well tests run about $210 to $220.

Compare kits for Illinois

Look up a well's drilling report in Illinois

What turns up in Illinois wells.

Share of tested wells over the limit, from lab tests the USGS, EPA and state agencies collected since 2000. Your own well needs its own test.

Tested wells over the limit, statewide
Nitrate19%79 of 423Arsenic18%35 of 195Manganese13%30 of 236Radon1%1 of 75Lead1%1 of 195Fluorideunder 1%1 of 230Uranium0%0 of 191
GermsTest every year, whatever the chart says
Coliform bacteria17%11 of 65
StainsNot a health risk
Iron stains70%165 of 236

Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+

Lab results: Water Quality Portal (USGS and EPA)

Where it shows up most

Find your county.

5 counties have a full report with local test results and well depths.

BooneChampaignCookMadisonMcHenry
Every county in Illinois: people on wells and typical depth
CountyPeople on private wellsShare of residentsTypical well depth
Lake County100,58014%154 ft
McHenry County79,78926%125 ft
Will County68,84010%160 ft
Cook County51,542under 1%200 ft
DuPage County49,2205%180 ft
Kane County47,4729%259 ft
Winnebago County41,42115%143 ft
LaSalle County24,77823%173 ft
Kankakee County22,81421%125 ft
Madison County20,1248%40 ft
Ogle County19,39337%205 ft
Rock Island County19,08713%240 ft
Peoria County18,89810%65 ft
Whiteside County18,64933%120 ft
Tazewell County18,02614%132 ft
Adams County15,65124%185 ft
Kendall County15,34712%280 ft
Sangamon County15,1418%40 ft
St. Clair County15,0056%83 ft
Boone County14,97828%167 ft
Champaign County14,9757%119 ft
Vermilion County14,33119%90 ft
McLean County13,3948%155 ft
Woodford County13,19134%140 ft
Henry County12,53525%284 ft
DeKalb County12,53412%200 ft
Macon County12,51412%90 ft
Jefferson County12,45534%63 ft
Williamson County12,37818%145 ft
Stephenson County12,27728%190 ft
Macoupin County11,31325%41 ft
Lee County11,29733%208 ft
Effingham County11,14532%47 ft
Franklin County10,96329%150 ft
Jo Daviess County10,09146%230 ft
Jackson County10,03619%215 ft
Grundy County9,63018%200 ft
Fayette County9,54044%41 ft
Iroquois County9,46235%138 ft
Christian County9,25427%41 ft
Saline County9,08638%135 ft
Monroe County9,07726%230 ft
Marion County8,98624%40 ft
Fulton County8,79626%65 ft
Clinton County8,65023%35 ft
Bureau County8,63426%200 ft
Shelby County8,58241%41 ft
Livingston County8,26923%90 ft
Randolph County7,93626%55 ft
Knox County7,73015%200 ft
Wayne County7,34945%120 ft
Crawford County7,27139%51 ft
Morgan County6,72720%41 ft
Hancock County6,66938%242 ft
Union County6,66339%264 ft
Montgomery County6,54323%40 ft
Hamilton County6,27979%250 ft
Bond County6,06436%40 ft
Clark County6,02839%65 ft
Perry County5,99529%38 ft
Coles County5,98713%65 ft
Jersey County5,97628%50 ft
Mercer County5,90938%422 ft
Washington County5,73142%40 ft
Richland County5,60935%180 ft
Jasper County5,60160%40 ft
Logan County5,54820%62 ft
Carroll County5,47535%252 ft
McDonough County5,44720%240 ft
Clay County5,35540%80 ft
Mason County5,32041%73 ft
Cumberland County5,21250%42 ft
Douglas County5,18026%72 ft
Edgar County4,96829%60 ft
Warren County4,89529%190 ft
Massac County4,78734%130 ft
Lawrence County4,75131%130 ft
Johnson County4,65035%249 ft
Moultrie County4,45431%82 ft
Pike County4,37630%132 ft
White County4,21330%175 ft
Piatt County4,03324%150 ft
De Witt County4,00126%165 ft
Menard County3,92732%45 ft
Greene County3,60330%44 ft
Henderson County3,29352%105 ft
Marshall County3,28128%106 ft
Wabash County3,21328%240 ft
Cass County3,05123%59 ft
Ford County2,94122%120 ft
Calhoun County2,91066%100 ft
Schuyler County2,55237%50 ft
Pulaski County2,46447%71 ft
Pope County2,33962%230 ft
Edwards County2,23336%59 ft
Stark County2,02538%98 ft
Hardin County1,93753%220 ft
Putnam County1,92834%178 ft
Scott County1,76036%50 ft
Brown County1,68127%300 ft
Gallatin County1,61233%100 ft
Alexander County1,58530%160 ft

Questions people ask about well water in Illinois

Does Illinois require private wells to be tested?

Illinois doesn't require routine testing of existing private wells. Keeping a well safe is up to the owner, so test for bacteria and nitrate every year.

Where can I get my well water tested in Illinois?

Otherwise, use a lab certified by Illinois for drinking water. The state's list is linked on this page.

Where these numbers come from

  • How many people use wells: EPA estimates from the 2020 Census.
  • Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000.
  • State programs and links: Illinois Department of Public Health.