Certification information

We certify operators to help ensure that they are knowledgeable and that wastewater treatment plants are properly operated and maintained. We certify operators based on wastewater operating experience and education. We have four levels of full certification. The requirements and allowable substitutions for each level are listed in the rule (WAC 173-230-250). Each level also requires passing an exam.

We also have four optional Operator in Training (OIT) Group Levels. If an operator doesn’t meet all the education and experience requirements, but believe they can pass the next Group Level exam, they may apply for an Operator in Training exam. The requirements and substitutions for each OIT level are listed in a different section in the rule (WAC 173-230-260). We do not require an operator to earn an OIT certification to advance to the next full certification level.

See our FAQ below for more information.

Frequently Asked Questions

Exam Information

Operating Experience

Maintaining Certification

Reciprocity