Median Pay by Area
- Portland-Vancouver-Hillsboro
- $83,860 a year
- Medford
- $73,270 a year
- Eugene-Springfield
- $70,250 a year
- Albany
- $67,060 a year
- Salem
- $65,270 a year
- Bend
- $62,310 a year
Oregon wastewater operators
The steps from no certificate to an Oregon Grade I wastewater collection or treatment certificate, what the exam is like, how to book it and what operators earn. Every requirement links to the Oregon Department of Environmental Quality.
DEQ makes the final eligibility determination. Check with DEQ before you apply.
Why it matters
Oregon law requires owners of wastewater systems to have their systems under the responsible control and direction of certified operators. DEQ runs the certification program for domestic wastewater operators; the Oregon Health Authority certifies drinking water operators.
The operator a system designates as its supervisor must hold a certificate at or above the system's classification. A shift or on-call supervisor of a Class II, III or IV system may be certified one grade lower.
Collection and treatment are separate certificates, each with Grades I, II, III and IV. There is also a Small Wastewater System certificate for small combined systems.
You do not need a lower grade first. You can apply for any grade whose education and experience requirements you meet.
Step 1
Grade I needs a high school diploma or GED and one year of operating experience at a domestic wastewater collection or treatment system. Part-time work counts when it is part of your regular duties.
A DEQ-approved Associate of Applied Science degree in water quality or wastewater technology, or an approved four-year science degree, can replace six months of that year. Confirm with DEQ in advance.
Experience in a related field, such as drinking water, industrial maintenance or a laboratory, can cover up to half of the experience requirement.
Step 2
Operator in Training (OIT): with a high school diploma or GED and a DEQ-approved training program, you can take the Grade I exam before you have a year of experience. After you pass, you have 36 months to gain the year of experience and send DEQ a post-exam application.
Provisional Grade I: a 12-month, non-renewable certificate for new operators who are gaining experience under a certified operator and are enrolled in or have finished approved training. It includes approval to take the Grade I exam.
DEQ-approved training includes:
Step 3
Create a Your DEQ Online account, then submit the Wastewater Operator Certificate application with documents that show your education and experience, and pay the fee online.
Fees range from $50 to $340 depending on the service, and most are non-refundable. The exact fee appears in the Payment tab once you pick the exam type and grade.
DEQ says eligibility review takes about four weeks. If something is missing, DEQ sends the application back with the reason and a deadline.
Step 4
When DEQ finds you eligible, it emails instructions to schedule your own exam time and place with PSI. Exams are computer-based and offered year-round, up to six days a week.
To see test centers and open dates, choose Check for Available Dates on PSI's Oregon page and pick your exam, such as Oregon Wastewater Treatment Grade 1.
Grade I and II collection and treatment exams are available in Spanish. You choose the language when you schedule.
You can take two exams on the same day if the test center has room.
Step 5
Renew every two years through Your DEQ Online with at least 2.0 wastewater CEUs approved by the Oregon Environmental Services Advisory Council. One renewal covers both a collection and a treatment certificate.
Passing a WPI exam, for example to move up a grade, can earn 2.0 CEUs toward renewal.
Exam day
Oregon uses the national standardized exams from Water Professionals International (WPI, formerly ABC). Since May 1, 2025 candidates take the 2025 version.
Each exam has 100 scored multiple-choice questions plus 10 unscored trial questions, including math problems. It is closed-book with a three-hour limit.
Scores are reported on a scale where 70 or higher passes.
The WPI Formula/Conversion Table for wastewater exams is provided at the test site, and you may use a non-programmable calculator.
Operator Master has free practice questions with an explanation after every answer, a timed full-length practice exam and step-by-step math help built on the WPI formula table. It is an independent study tool, not the official exam.
Pay
The median pay for water and wastewater treatment plant and system operators in Oregon was $69,720 a year ($33.52 an hour) in 2025, compared with $60,020 nationally. One in ten earned $50,270 or less, and one in ten earned $87,880 or more.
These federal figures cover drinking water and wastewater operators together, at every grade. Pay for a new operator is usually nearer the low end.
Moving up
These are the times with a high school diploma or GED only. College or approved CEUs in applied or technical sciences shorten them, and Treatment Grade IV also needs one year of post-high school education.
From another state
If you hold a wastewater certificate in good standing from another state or Canadian province, or a WPI Professional Operator certificate, you can apply through Your DEQ Online and answer Yes to the reciprocity question. You still need to meet Oregon's education and experience requirements.
If you passed a standardized ABC or WPI exam, DEQ can waive the exam at the same grade. If you passed a state-written exam, the waiver is one grade lower.