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Administration & RecordsIntermediate 15 min read

Missouri Wastewater Treatment Operator Certification Guide

Overview of Missouri's DNR wastewater operator certification structure (Class D-A), renewal requirements, and regional operating context.

Missouri Wastewater Treatment Operator Certification
Regulatory Authority
Wastewater treatment operators in Missouri are certified by the Missouri Department of Natural Resources (DNR), Water Protection Program. Certification is issued across four classes — Class D through Class A, with Class D being the entry-level credential and Class A covering the largest, most complex facilities.
Certification Structure
  • Class D — entry-level, smallest facilities
  • Class C — moderate-size facilities
  • Class B — larger facilities
  • Class A — the largest and most complex municipal and industrial wastewater treatment plants
Operators must pass a state exam with a 70% passing score, covering Missouri wastewater regulations, general systems knowledge, water quality, applied math, chemistry, laboratory procedures, hydraulics, and pumps.
Renewal
Certificat

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