Missouri county well guide

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

About 4,033 households in Warren County, 30% of the county, rely on a private well. Nobody tests that water unless the owner does.

Labs within 40 milesLicensed contractors
30%of households on a private well
Share on wells, county vs state
Warren County30%
Missouri average14%
8licensed contractors serve the county
24 mito the nearest certified lab, R.M. Wester and Associates Inc.
Nostatewide test required when a home is sold

About one in 3 households in Warren County relies on a private well, around 4,033 homes. Outside the towns with public water, wells are the norm here.

Local rules for wells in Warren County

The rules that apply in Warren County are set at the state level in Missouri. New wells must be tested before use, and nothing is required at sale. Some counties and townships add permits or setbacks of their own, so check locally before drilling. The state's own recommendations are below.

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 Warren County

The nearest certified lab is R.M. Wester and Associates Inc. in St. Peters, about 24 miles from the county center. There are 7 more within 40 miles, listed below with what each tests for.

8 certified labs within 40 miles

Licensed well contractors serving Warren County

Licensed help in Warren County includes Brute LLC and Crawford DRLG DBA Wideman Well and 6 others. Every listing was matched to the Missouri license list; the "verify" link on each profile opens the state lookup.

Well depth and water chemistry

Well depth and water chemistry in Warren County follow the rock underneath it. Typical wells here run 460 to 600 feet; the median of 2,337 domestic wells certified to the Missouri Geological Survey since 2000 is 520 feet. Contaminants worth testing for in this part of Missouri include 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).

Typical well depth

460 to 600 feet; the median of 2,337 domestic wells certified to the Missouri Geological Survey since 2000 is 520 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: Lincoln County, Montgomery County, St. Charles County, Franklin County.

What well work costs in Warren 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 Warren County well owners ask

How many homes in Warren County are on a well?

About 4,033, or 30% 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 Warren County?

R.M. Wester and Associates Inc. in St. Peters, about 24 miles away. Call first to ask whether they accept homeowner samples.

Do I need a permit to drill a well in Warren 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 Warren 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.