Median Pay by Area
- Lewiston (Idaho-Washington)
- $61,830 a year
- Boise City
- $58,640 a year
- Twin Falls
- $56,520 a year
- Coeur d'Alene
- $56,380 a year
- Idaho Falls
- $50,680 a year
Idaho wastewater operators
The steps from no license to an Idaho Wastewater Treatment Class I license, how to book the exam with PSI, how to keep your license active and what operators earn. Every requirement links to the Idaho Division of Occupational and Professional Licenses (DOPL) or the Idaho rule and law it follows.
DOPL makes the final eligibility determination. Check with DOPL before you apply.
Why it matters
Idaho law requires a license to operate, or be in responsible charge of, a public wastewater system. Operating personnel include anyone making decisions about the system that may affect public health.
The operator a system designates as its responsible charge operator must be licensed at a class equal to or higher than the system's classification. Licenses are issued by DOPL for the Idaho Board of Drinking Water and Wastewater Professionals.
Wastewater Treatment Operator licenses come as Operator-In-Training, Class I Restricted, Class I, II, III and IV, and Land Application. Idaho also licenses Wastewater Collection Operators, Wastewater Laboratory Analysts and Very Small Wastewater Systems separately.
A Very Small Wastewater System serves 500 connections or fewer, has a small collection system and uses only one treatment process: lagoons, primary treatment, or primary treatment discharging to a large soil absorption system.
You can apply and test for the class whose education and experience requirements you meet.
Step 1
Every operator license needs a high school diploma, GED or equivalent, and you must be a lawful resident of the United States.
Wastewater Treatment Class I needs 1,600 hours of relevant on-site operating experience, or completion of a board-approved Class I apprenticeship program.
College in environmental control, engineering or a related science can replace up to half of the experience. Thirty college credits, or 45 CEUs of germane continuing education, count for 1,600 hours.
At least half of your experience must be hands-on in the license type you are applying for. The rest can come from related work, such as drinking water operation, environmental consulting or building treatment and collection systems.
Step 2
Operator-In-Training: pass the board-approved exam or enroll in a board-approved apprenticeship program. The license is valid for five years, and you must work under the direct supervision of an appropriately licensed operator.
Class I Restricted: 260 hours of relevant on-site experience during 12 consecutive months with a system, plus 16 hours of continuing education relevant to the license. The license is limited to that one system.
Very Small Wastewater: 88 hours of relevant on-site experience, 6 hours of pumps and motors or collection courses, and 6 hours of lagoon, large soil absorption system or wastewater treatment courses.
Step 3
WPI's Need-to-Know Criteria outline the content and job tasks covered on its standardized exams. The 2025 criteria include separate documents for Wastewater Treatment Operator Class I, II, III and IV.
WPI lists approved study references, including Operation of Wastewater Treatment Plants, Volumes I and II, from the Sacramento State Office of Water Programs, and WEF Wastewater Treatment Fundamentals. DOPL's training page also points to the Office of Water Programs for exam study materials.
WPI says to check with your state's certifying authority about which study materials fit your exam and exam date.
Step 4
Since July 17, 2023, you must take and pass the exam before you apply to DOPL for a license. Sign up with PSI, including for a retake after a failing score.
On PSI's Idaho page, create an account, choose View Available Tests, pick your exam, such as Idaho Wastewater Treatment Class 1, and submit the test application. Then sign in with the same account to schedule.
Idaho exams are given at PSI test centers. Arrive at least 30 minutes early with a valid government photo ID. Only a silent, battery-operated, non-programmable calculator is allowed.
Need help scheduling? DOPL lists PSI's number: 833-256-1420.
Step 5
After you pass, apply through DOPL Online Services with documents that show your education and experience. Exam scores are valid for one year from the exam date.
DOPL's wastewater work verification form is completed with your employer and signed by your supervisor. Self-verification is not accepted.
DOPL lists a $25 initial application fee and a $30 original license fee. Fees are non-refundable.
Step 6
Licenses expire on your birthday. DOPL is moving licenses from one year to two years, and once you renew for two years the license fee doubles to cover both years. You can renew up to 60 days early.
To renew, complete and keep proof of 6 classroom hours (0.6 CEUs) of continuing education for each year of the licensing period, germane to wastewater. Online courses count when they are germane. You can carry forward up to 6 unused hours for one renewal cycle.
Since July 1, 2024, wastewater courses no longer need prior board approval; they only need to be germane to the profession. DOPL says safety training such as first aid counts, while soft-skill and computer courses do not.
Holding more than one wastewater license needs only one set of wastewater hours. Keep each certificate of completion showing the provider, your name, the date, the credits and the type (wastewater); DOPL audits renewals.
Exam day
Idaho's exams, including Wastewater Treatment Class 1 through 4, Small Wastewater System/Lagoon and Land Application, are listed on PSI's ABC testing site. ABC Testing is a Water Professionals International (WPI) service.
WPI's standardized wastewater treatment exams come with the WPI Formula/Conversion Table, which lists the formulas and common abbreviations that may appear on the exam.
Phones and other electronic devices are not allowed in PSI test centers, and personal items should be left elsewhere.
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 Idaho was $52,210 a year ($25.10 an hour) in 2025, compared with $60,020 nationally. One in ten earned $40,820 or less, and one in ten earned $74,950 or more.
These federal figures cover drinking water and wastewater operators together, at every class. Pay for a new operator is usually nearer the low end.
Moving up
These are Idaho's Wastewater Treatment Operator classes. Each also needs a high school diploma or GED. Related college or germane continuing education can replace up to half of the experience, and a board-approved apprenticeship can stand in for the education or experience.
From another state
If you hold a valid wastewater operator license from another state whose requirements are not lower than Idaho's, the board can accept you for an Idaho license when you apply and pay the fee. DOPL lists a $30 endorsement fee.
Ask each state where you are or were licensed to send a license certification directly to DOPL at BCRE-Licensing@dopl.idaho.gov.