Missouri county well guide

Well Water in Jefferson County, MO: Testing, Contractors and Rules

About 19,258 households in Jefferson County, 22% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
22%of households on a private well
Share on wells, county vs state
Jefferson County22%
Missouri average14%
21licensed contractors serve the county
22 mito the nearest certified lab, Pace Analytical Services LLC-Hazelwood
Nostatewide test required when a home is sold

Jefferson County has an estimated 19,258 households on private wells, 22% of the county. If you are one of them, testing, treatment and repairs are yours to arrange.

Local rules for wells in Jefferson County

Private wells in Jefferson County follow Missouri's statewide rules, administered by Missouri Geological Survey, Well Installation Section, in the Department of Natural Resources. A water test is required when a new well is completed. There is no statewide test requirement when a home is sold, though lenders often ask for one. The cards below show the details and the official sources.

At a glance

Water test for a new wellRequired

No permit for the owner, but the well must be built by a Missouri permitted well installation contractor to the 10 CSR 23-3 standards for its drilling area (Missouri has 13 drilling areas with different minimum casing depths, grouted casing, 50 ft from a septic tank and 100 ft from a lagoon or drainfield), and the contractor must disinfect the well, take a water sample for bacteria after construction and file a well certification report with the Missouri Geological Survey within 60 days. The State Public Health Laboratory's New Well Series (pH, fluoride, chloride, nitrate, sulfate, iron, manganese and lead) is the usual chemistry check on a new well.

Water test when a home is soldNot required statewide

No statewide requirement. The Missouri seller's disclosure asks only whether the water supply is a private well and whether the seller knows of problems. FHA, VA and USDA loans normally require a bacteria, nitrate and lead sample from a certified lab before closing.

What the state recommends

The Department of Health and Senior Services recommends testing a private well every year for coliform bacteria, and every few years for nitrate, pH, hardness, iron, manganese, lead and copper (the State Public Health Laboratory's minerals, nutrients and metals panel covers all of these plus arsenic and uranium). Add radon and radium in the Ozarks, lead and cadmium in the Old Lead Belt and Viburnum Trend mining districts, sulfate and chloride in deep northern wells, pesticides in shallow Bootheel wells, and test again after flooding, well work or a change in taste, color or smell. Karst wells and springs in the Ozarks should be retested after heavy rain.

Free or low-cost testingAvailable

No free program, but the cheapest state lab in the country: the State Public Health Laboratory tests a private well or cistern sample for total coliform and E. coli for a $10 handling fee. Pick up the kit from your local public health agency or district health office, collect the sample and hand it back for the lab's free statewide overnight courier. Chemistry panels cost more and are ordered through the same agency or the Bureau of Environmental Epidemiology (573-751-6102).

Getting your water tested near Jefferson County

10 certified labs within 40 miles serve Jefferson County, starting with Pace Analytical Services LLC-Hazelwood in Hazelwood (about 22 miles from the county center). Each card below shows whether the lab takes homeowner samples and which tests it is certified for.

9 certified labs within 40 miles

Licensed well contractors serving Jefferson County

21 licensed contractors serve Jefferson County, including A&M Pump Inc and Arnold Drilling & Pump. Each profile carries the state license number and the date we checked it, and the filters below sort them by drilling, pump work or treatment.

Well depth and water chemistry

Wells in Jefferson County typically reach 300 to 470 feet; the median of 3,077 domestic wells certified to the Missouri Geological Survey since 2000 is 380 feet. What comes up with the water depends on the aquifer, and across Missouri the usual suspects are coliform bacteria (the most common failure statewide, worst in ozark karst wells and springs after rain), nitrate (shallow wells in farm country, the bootheel and northern missouri). A first full panel tells you which of them apply to your well.

Typical well depth

300 to 470 feet; the median of 3,077 domestic wells certified to the Missouri Geological Survey since 2000 is 380 feet

Contaminants to test for
  • Coliform bacteria (the most common failure statewide
  • Worst in Ozark karst wells and springs after rain)
  • Nitrate (shallow wells in farm country
  • The Bootheel and northern Missouri)
  • Hardness (dolomite across the Ozarks)
  • Iron and manganese (glacial till
  • Alluvium and Bootheel sands)
  • Radon and radium (locally in the Ozark aquifer)
  • Lead
  • Cadmium and zinc (Old Lead Belt
  • Viburnum Trend and Tri-State mining districts)
  • Sulfate
  • Chloride and sodium (deep bedrock wells in northern and western Missouri)
  • Arsenic (locally)
  • Pesticides (shallow Bootheel and river-bottom wells)
  • PFAS near airfields and industrial sites

Neighboring counties: St. Louis County, Franklin County, Washington County, St. Charles County.

What well work costs in Jefferson County

Basic bacteria and nitrate test$25 to $75lab fee, homeowner sample
Full panel lab test$150 to $400metals, VOCs, radiologicals
Well inspection$250 to $550flow, pressure, visual, water test
Submersible pump replacement$1,200 to $4,500parts and labor
Pressure tank replacement$400 to $1,200installed
Whole-house treatment system$800 to $6,000softener, iron filter, UV, RO
New well drilled$5,500 to $25,000about $25 to $65 per foot
Shock chlorination$80 to $300or about $20 as a DIY job

National ranges from published 2025 to 2026 contractor pricing. Local quotes vary with depth, access and materials.

Questions Jefferson County well owners ask

How many homes in Jefferson County are on a well?

About 19,258, or 22% of households, based on Census housing data and state well surveys. The share is highest outside the towns with public water.

Where is the closest certified lab to Jefferson County?

Pace Analytical Services LLC-Hazelwood in Hazelwood, about 22 miles away. Call first to ask whether they accept homeowner samples.

Do I need a permit to drill a well in Jefferson County?

No permit for the owner, but the well must be built by a Missouri permitted well installation contractor to the 10 CSR 23-3 standards for its drilling area (Missouri has 13 drilling areas with different minimum casing depths, grouted casing, 50 ft from a septic tank and 100 ft from a lagoon or drainfield), and the contractor must disinfect the well, take a water sample for bacteria after construction and file a well certification report with the Missouri Geological Survey within 60 days. The State Public Health Laboratory's New Well Series (pH, fluoride, chloride, nitrate, sulfate, iron, manganese and lead) is the usual chemistry check on a new well.

What does a well test cost near Jefferson County?

A bacteria and nitrate test runs $25 to $75 at most certified labs; a full panel with metals is $150 to $400. Mail-in kits cost about the same as walking in.