Missouri Private Wells: Well Condition, Pumps and Testing per MU Extension

MU Extension fact sheet EQM103F (Home-A-Syst series; author Steve Mellis; date not stated). Only stated points are included. Regulatory distances cite rules dated June 1996 and may have changed.

Key points from the page

Missouri has more than 400,000 private wells, and more than 1.4 million Missourians use them.
A 1994 state health department survey of 861 wells found 56% positive for total coliform and 22% positive for E. coli.
Older wells: those over 50 years are likely shallow and poorly built; casings of 30 to 40 years may corrode. Older pumps may leak lubricating oil or contribute lead.
The casing should extend at least 12 inches above ground (2 feet above the highest recorded flood level where flooding occurs), with ground sloping away from the wellhead.
The cap should be firmly attached with a vent that allows only air to enter; wiring should be secured in electric conduit.
Backflow: keep an air gap, or use a backflow prevention device such as a check valve or vacuum breaker.
An inspection is advised every 10 to 15 years (Not verified: who should perform it, and the "when problems are suspected" trigger, were not re-confirmed).
Test every year for the four common indicators: bacteria, nitrates, pH and total dissolved solids; the page also advises testing for lead (Not verified: the specific triggers listed in this article's earlier draft).
Abandoned wells can channel contaminants and are covered in a section on abandoned wells and cisterns with a DNR contact (Not verified: who may perform the closure).

Not verified: current Missouri well construction rules, which differ from the 1996 text cited. Confirm with the state DNR and your county health department.

General information only. Not health, plumbing, legal or code advice.