Washington certification guide

How Does Washington Wastewater Certification Work?

Learn the certification process, understand the requirements, and explore official Washington guidance.

Full certification

Washington Wastewater Operator Group I

The first full-certification level. It is separate from Group I Operator in Training.

What education do I need?: High school diploma or GED.
How much operating experience do I need?: One year of operating experience gained under the direction or supervision of a fully certified operator.
Do I need to pass an exam?: Required after Ecology approves the application.

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Full certification

Washington Wastewater Operator Group II

A higher full-certification level requiring more operating experience than Group I.

What education do I need?: High school diploma or GED.
How much operating experience do I need?: Three years of operating experience gained under the direction or supervision of a fully certified operator.
Do I need to pass an exam?: Required after Ecology approves the application.

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Full certification

Washington Wastewater Operator Group III

An advanced full-certification level with college-equivalent education and Class II-or-higher plant experience conditions.

What education do I need?: High school diploma or GED plus two years of college, defined in the table as 90 credits or CEUs.
How much operating experience do I need?: Four years, including at least two years at a Class II or higher plant.
Do I need to pass an exam?: Required after Ecology approves the application.

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Full certification

Washington Wastewater Operator Group IV

Washington's highest full-certification group, with four-year college-equivalent education and Class III-or-higher plant experience conditions.

What education do I need?: High school diploma or GED plus four years of college, defined in the table as 180 credits or CEUs.
How much operating experience do I need?: Four years, including at least two years at a Class III or higher plant.
Do I need to pass an exam?: Required after Ecology approves the application.

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Operator in Training

OIT Is a Separate, Optional Credential Path.

A person without a full certification may apply only for Group I OIT. A currently certified operator may apply for an OIT one level above the full certification. OIT is not required before full certification.

Review OIT education and experience credit

Why am I seeing this?

WAC 173-230-260 — Education and experience requirements for OIT certificationsWashington State Department of EcologyWAC 173-230-260, Table 3 · Verified 2026-07-28

Creates optional OIT I–IV pathways, limits which OIT level an applicant may seek, and specifies the experience needed to upgrade to full certification.

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Certification informationWashington State Department of EcologyEcology Wastewater Operator Certification — Certification information · Verified 2026-07-28

Provides current application, exam administration, operating-experience, OIT, maintenance, reciprocity, study-resource, and contact guidance.

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