Private well guide

Well Water in Missouri: Testing, Rules, Labs and Licensed Contractors

328,845 households in Missouri get their water from a private well. Here is what the state requires, where to get it tested, and who is licensed to work on it.

Find a certified labLicensed contractorsPick my county
372Licensed contractorschecked against state records
27Certified labsfrom the state certified list
114Counties covered
328,845Households on wells14% of households (est.)

About 330,000 Missouri households, one in seven, draw their water from a private well, and in the Ozark counties it is two thirds to more than 80% of homes. Missouri drills deeper for house water than any state around it, keeps one of the best well databases in the country, and runs the cheapest state bacteria test anywhere: $10, kit from your county health office, free courier to Jefferson City.

Who is in charge of a Missouri well

The Missouri Geological Survey’s Well Installation Section in Rolla permits the people who drill wells and install pumps under the Water Well Drillers’ Act and writes the construction rules in 10 CSR 23, which divide the state into 13 drilling areas with different minimum casing depths because the geology changes so much from the Ozarks to the glacial north. The owner needs no permit, but the well must be built by a permitted contractor, disinfected and sampled for bacteria, and certified to the Survey within 60 days; those certification reports, nearly 200,000 of them, are searchable in the WIMS system with depth, casing, yield and static water level. DNR certifies the laboratories for public water systems. Water quality in a private well belongs to the Department of Health and Senior Services, whose State Public Health Laboratory tests private samples that come in through the local public health agencies.

What is required, and what is left to you

A permitted contractor, construction to the drilling-area standard, disinfection, the bacteria sample at completion and the certification report. After that, nothing: Missouri does not require a test of private well water at any later point, including when the house is sold. The Department of Health’s advice is a coliform bacteria test every year, and a chemistry check every few years, which the state lab makes easy with its New Well Series and its minerals, nutrients and metals panel. In the Ozarks, retest after heavy rain.

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).

What the water is like

South of the Missouri River the Ozarks are a thick stack of dolomite riddled with caves, springs and losing streams, and domestic wells go 300 to 800 feet to reach reliable water: hard, usually clear, but connected to the surface through karst, so bacteria and turbidity after storms are the common failures and any well near a sinkhole deserves a UV unit. Radon and radium turn up locally, and in the Old Lead Belt around Flat River and the Viburnum Trend, and the Tri-State district around Joplin, lead, cadmium and zinc from mining can reach shallow wells. North of the river the glacial till holds little water, and what it holds is high in iron, manganese, sulfate and sometimes nitrate, which is why so much of northern Missouri is on rural water districts and wells there are shallow and few. The Bootheel and the Missouri River bottoms have plentiful shallow alluvial water with iron and, in farm country, nitrate and pesticides. Around St. Louis and Columbia, wells go 400 to 700 feet into the same Ozark aquifer, and at the northern edge it turns salty with depth.

Certified labs and the State Public Health Laboratory

DNR certifies drinking water laboratories for public water system compliance, and many of the certified microbiology labs are county health departments that test private well samples over the counter. The State Public Health Laboratory in Jefferson City is the backbone: a $10 bacteria kit from any local public health agency, returned by the state’s free courier, plus chemistry panels ordered through the same office. The commercial labs below, most of them in St. Louis, Kansas City, Springfield and the Lake of the Ozarks area, handle metals, VOCs, radon and PFAS. Every lab comes from the DNR certified lists, with the tests each is certified to run.

27 certified labs

See all 27 certified labs in Missouri

Permitted well and pump installation contractors

Missouri permits the individual, not the company. Every profile below is built from the WIMS permit search, grouped under the business each permit holder works for, with each permit number and what it covers: water well, pump installation, heat pump or monitoring well, and whether it is restricted. Where the Survey’s well database has certification reports under a permit, the profile shows how many wells the business has filed since 2016, the counties it works in and the typical depth it drills to.

372 licensed contractors

See all 372 licensed contractors in Missouri

By county

Well use runs from almost nobody in Jackson, Clay, Platte and St. Louis counties to two thirds of homes in Shannon, Maries, Washington and Reynolds and more than 80% in Bollinger and Ozark. Thirteen northern and Bootheel counties served entirely by rural water districts show only the handful of wells on record. Each county page carries its well population, the typical depth of domestic wells certified to the Survey since 2000, the nearest certified labs and the permitted contractors based there.

Missouri well water questions

Do I need a permit to drill a well in Missouri?

Not as the owner. Your contractor must hold a Missouri well installation permit, build the well to the rules for your drilling area, disinfect and sample it, and file the certification report within 60 days. Some counties and the St. Louis area have local plumbing and health rules on top of the state’s.

Is a water test required when I sell my house?

No. Missouri has no statewide requirement. Government-backed mortgages require a bacteria, nitrate and lead test before closing, so most sales include one anyway.

How do I find the record for my well?

Search WIMS by owner name, address, county or map location. Reports go back to 1987 and show the contractor, depth, casing, yield and static water level; the Survey can look up older wells by request at 573-368-2165.

How do I get the $10 bacteria test?

Pick up a State Public Health Laboratory kit from your county or city health department, collect the sample the way the instructions say, and return it the same day so it reaches the courier; results come back in about a week. The same office can order the chemistry panels.

Why is my well so deep?

Because you live in the Ozarks. The dolomite that makes up the Ozark aquifer is hundreds of feet thick and the water table sits far below the hilltops, so 400 to 600 feet is normal and 800 is not rare. The depth also gives you casing through the karst zone, which is your best protection against bacteria.