Median Pay by Area
- Denver-Aurora-Centennial
- $76,150 a year
- Boulder
- $74,270 a year
- Grand Junction
- $73,920 a year
- Fort Collins-Loveland
- $73,330 a year
- Colorado Springs
- $65,970 a year
- Greeley
- $65,840 a year
Colorado wastewater operators
The steps from no certificate to a Colorado Wastewater Treatment Class D or Collection Class 1 certificate, how to apply for and pass the exam, how to keep your certificate active and what operators earn. Every requirement links to the Colorado Department of Public Health and Environment (CDPHE), the Colorado Certified Water Professionals (CCWP) program that runs certification for the Water and Wastewater Facility Operators Certification Board, or the board's Regulation 100 (5 CCR 1003-2).
CCWP makes the final eligibility determination. Check with CCWP before you apply.
Why it matters
Colorado law requires every domestic or industrial wastewater treatment facility and every wastewater collection system to be under the supervision of a certified operator holding a certificate in a class equal to or higher than the class of the facility or system.
The facility owner designates one or more certified operators in responsible charge (ORC). Process control decisions that may affect public health or the environment must be made by an ORC, or by another operator certified at or above the facility's class under the facility's written operating plan.
An operator is anyone who does work that is part of running a water or wastewater facility, and an operator may or may not be certified. Some small facilities are exempt from needing a certified operator; Regulation 100 lists them.
Colorado wastewater treatment certificates are Wastewater Treatment Class D (entry level), Class C, Class B and Class A (most advanced). Industrial Wastewater Treatment certificates use the same D to A classes.
Wastewater collection certificates are Collection Class 1 (entry level), Class 2, Class 3 and Class 4 (most advanced).
The Small Wastewater System certificate (Class S) is an entry-level certificate that combines treatment and collection. Its holder can be the operator in responsible charge of a Class D treatment facility or a Class 1 collection system serving fewer than 3,300 people.
CDPHE classifies each treatment facility by its treatment processes and design flow, and each collection system by population served: Class 1 serves 3,300 people or fewer, Class 2 serves 3,301 to 25,000, Class 3 serves 25,001 to 100,000 and Class 4 serves over 100,000. Large lift stations or significant industrial users can raise a Class 1 or 2 system's class.
Step 1
Certification is handled online in the CCWP Portal. Creating an account gives you an Operator ID number. The number identifies you in the portal, but it does not make you a certified operator yet.
Give your Operator ID when you register for training, so the instructor can upload your training units (TUs) to your portal account. You then claim those training units in the portal.
Step 2
Every new applicant must complete an approved mandatory regulatory training (MRT) course before applying. An application without it is incomplete.
CDPHE offers free, on-demand wastewater and water MRT courses online through Indigo Water Group. You need your Operator ID number to register.
Each MRT completion is valid for three years. One wastewater MRT course can count toward wastewater treatment, industrial wastewater and collection certificates.
Step 3
You need a high school diploma or GED. Without one, you can substitute an extra 6 months of qualifying experience plus 1.0 training unit in an approved course, so you need 7 months of experience in all.
Class D, Class 1 and Class S exams need 1 month of hands-on experience under a certified operator in responsible charge. An approved course of study (usually 35 hours or more) or an approved apprenticeship can take its place.
Enter your education, experience and training in the portal. Upload proof of education, such as a diploma, equivalency certificate or college transcript.
Step 4
Choose your exam under Apply for Certification in the CCWP Portal. Every eligibility item must show a green check mark, and you agree to the Colorado Certified Water Professionals Code of Conduct.
Pay the $50 application fee in the portal. Applications are reviewed within about 10 business days.
If the reviewer needs more information, you have 90 days to fix the issues and resubmit, or the application is denied. A denied applicant can appeal to the board within 30 days.
Step 5
Once you are approved, you receive an email with instructions to create or log in to your PSI account and schedule the exam. Scheduling happens with PSI, not in the CCWP Portal. You can also call PSI at 833-256-1420.
Pay the $104 exam fee to PSI when you schedule. Exam fees are not refundable or transferable.
You can test at a PSI test center (10 in Colorado and more than 300 across the country) or by live remote online proctoring, if your computer, room and internet connection meet PSI's requirements.
Bring one current photo ID with your signature, such as a driver's license, state ID card or passport. Missing the appointment or arriving more than 15 minutes late forfeits your exam fee.
Step 6
You need a score of 70% or better. Once you pass and are notified through the CCWP Portal, you can download and print your new certificate there.
A new certificate is valid for three years from its effective date.
Step 7
To renew, you need a current MRT completion and enough training units: 1.2 for Class D or Class 1, 1.8 for Class C, Class 2 or Class S, 2.4 for Class B or Class 3 and 3.0 for Class A or Class 4. The MRT counts within that total.
At least half of the training units must come from courses approved for the category you are renewing, such as domestic wastewater treatment or collection. One training unit equals 10 contact hours. Training units are earned while the certificate is valid and do not carry over to the next three years.
Search CCWP's course catalog for approved courses, then apply for renewal from your portal dashboard. The renewal fee is $85, and renewals are reviewed in about 10 business days.
A certificate stops being valid on its expiration date. You can restore it for up to two years with a $100 late fee; after that it is revoked and you must start over with the entry-level exam.
Exam day
Colorado uses standardized, sequential exams developed by Water Professionals International (WPI) for every class except Class S and Class T, which are custom Colorado exams. WPI publishes Need-to-Know Criteria for each exam.
For the custom Small Wastewater System exam, CDPHE says to review WPI's Class I Need-to-Know Criteria for both wastewater treatment and wastewater collection.
Exams are taken on computer. Questions are multiple choice (A to D), shown one at a time, and you can skip or bookmark questions and come back. A short practice tutorial comes first and does not count toward your exam time.
You pass with 70% or better. Your result shows on screen, and you get an analysis of how you did on each topic. You cannot review your individual answers.
At a test center, PSI gives you pencils and ABC's standard formula sheet at check-in, plus one sheet of scratch paper at a time. For remote exams, the ABC formula table and an onscreen calculator are in the testing software.
You may use a silent, non-programmable calculator without letter keys or printing. Phone calculators are not allowed.
If you fail, you may retest within the 100-day eligibility period without paying another application fee, but each retake has a new exam fee.
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 Colorado was $74,200 a year ($35.68 an hour) in 2025, compared with $60,020 nationally. One in ten earned $50,130 or less, and one in ten earned $95,730 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
Exams must be passed in order, so you cannot skip from Class C to Class A or from Class 2 to Class 4. The prior certificate must be in the same category. The experience does not have to be at the level of the exam. Post-secondary education or approved training can replace up to half the experience for Class C and above, and domestic and industrial wastewater treatment experience count the same.
From another state
Colorado may certify you without an exam if you hold a valid certificate in good standing from another state or country, passed a Colorado-approved exam for that category and class with 70% or better, and meet Colorado's education and experience requirements. Colorado-approved exams are standard WPI exams and California or Texas operator exams.
Your experience must be gained where you hold the certificate, and you must complete Colorado's MRT. If your education and experience fall short, you can be certified at the level they qualify you for in Colorado.
If you have not passed a Colorado-approved exam, the reviewer may let you skip the sequential exams and sit for an advanced Colorado exam. You must pass it within the 100-day exam window or start over at the entry level.
Apply for certification by reciprocity in the CCWP Portal with a copy of your current certificate; expired certificates are not considered. The application fee is $150, and review takes about 10 business days.