On-site wastewater treatment system designer. "Designer" or "licensee" means an individual authorized under chapter 18.210 RCW to perform design services for on-site wastewater systems.

On-site wastewater treatment system inspector/certificate of competency holder. "Certificate of competency holder" or "inspector" means a person who has been issued a certificate and has been authorized by the board to practice as an on-site wastewater treatment inspector.