TCEQ Class C Wastewater Practice Test
Original questions written to TCEQ’s Need-to-Know Criteria for this license, every option explained.
Why is sludge thickened before digestion or dewatering?
335 original TCEQ Class C Wastewater questions with explanations · 100-question practice exam · 9 subjects
TCEQ Class C Wastewater exam format
The Texas Commission on Environmental Quality licenses wastewater operators. The Class C criteria cover the Class D subjects in more depth, with recommended monitoring and testing for 1.0 to 5.0 MGD plants and solids control. You need 70 percent to pass, at a TCEQ-approved computer-based testing center.
- Subjects (TCEQ Need-to-Know)
- Statutes, rules, permits and design criteria, Safety and management, Laboratory and process control, Collection and pumping, Preliminary and primary treatment, Ponds, trickling filters and activated sludge, Disinfection and effluent disposal, Sludge digestion and biosolids, Math
- Where
- At a TCEQ-approved computer-based testing (CBT) center after TCEQ approves your application; scores are immediate
- Passing score
- 70 percent
- Fees
- TCEQ application $111 ($74 provisional Class D); each CBT center sets its own testing fee
- Allowed aids
- A non-programmable calculator; scratch paper from the proctor. No books or notes
- Questions and time
- TCEQ does not publish the number of questions or the time limit for this exam
- Requirements
- High school diploma or GED and two years of experience, at least half in wastewater treatment (up to one year can be replaced by college hours or extra training)
- Required training
- Basic Wastewater Operation and Activated Sludge or Wastewater Treatment, plus one elective
What’s on the TCEQ Class C Wastewater exam
TCEQ lists these subjects without question counts. Our practice exam gives each subject an equal share; each row links to the free topic drills that practice it.
| Subject | What it covers | Our practice exam | Drill |
|---|---|---|---|
| Statutes, rules, permits and design criteria | TCEQ authority, discharge permits, self-reporting and design criteria | 11 | Permits and rules drill |
| Safety and management | Hazards and safe work; management decisions | 11 | Safety drillManagement drill |
| Laboratory and process control | Monitoring, sampling and testing for small plants and solids control | 11 | Wastewater lab drill |
| Collection and pumping | Collection parts, pumps and pumping installations | 11 | Collection maintenance drillCleaning and inspection drillI/I and overflows drill |
| Preliminary and primary treatment | Screens, grit removal and primary clarifiers | 11 | Primary treatment drill |
| Ponds, trickling filters and activated sludge | Ponds, fixed-film units and activated sludge | 11 | Activated sludge drillFilters and ponds drill |
| Disinfection and effluent disposal | Chlorination, dechlorination, alternatives, effluent disposal and reuse | 11 | Disinfection and effluent drill |
| Sludge digestion and biosolids | Digestion, thickening, dewatering and biosolids | 11 | Sludge and biosolids drill |
| Math | Geometry and algebra for flow, pumping and treatment | 12 | Wastewater math drill |
How to take the TCEQ Class C Wastewater exam
- Complete the required training (Basic Wastewater Operation and Activated Sludge or Wastewater Treatment, plus one elective) and meet the education and experience rules.
- Submit the TCEQ application and $111 fee (online through OLEA or by mail).
- Once TCEQ approves the application, schedule the exam at a TCEQ-approved computer-based testing center and pay its testing fee.
- Score 70 percent or more; results are immediate, and some centers offer one retest the same day.
Common questions
What is on the TCEQ Class C Wastewater exam?
TCEQ's Need-to-Know Criteria list the subjects: Statutes, rules, permits and design criteria, Safety and management, Laboratory and process control, Collection and pumping, Preliminary and primary treatment, Ponds, trickling filters and activated sludge, Disinfection and effluent disposal, Sludge digestion and biosolids, Math. TCEQ does not publish how many questions each subject gets.
What score do I need to pass?
TCEQ requires a minimum score of 70 percent.
How many questions are on the exam?
TCEQ does not publish the question count or time limit for this exam. Our practice exam has 100 questions on a 3-hour clock so you can practice at full length.
What can I bring to the exam?
A non-programmable calculator. The proctor supplies scratch paper and collects it. Phones, books and notes are not allowed.
Are these the real TCEQ questions?
No. TCEQ prohibits sharing or copying exam content. These are original questions written to TCEQ’s published Need-to-Know Criteria, with an explanation for every option.
Ready for exam day?
100 questions across the published subjects, with a score for every area and an explanation for every option.
Or start with a free ten-question drillMore Texas exam practice
One water operator pass covers every practice exam on the site.
Requirements, subjects, fees and pass mark checked November 2026 on tceq.texas.gov: TCEQ: Wastewater Treatment Plant and Collection System Operators · TCEQ: What applicants for wastewater licenses need to know · TCEQ: Licensing exams (computer-based testing, authorized aids) · TCEQ: Continuing education hours to renew by license type (PDF).
Game Assessment Prep is an independent practice site, not affiliated with or endorsed by Water Professionals International (WPI, formerly ABC), the California State Water Resources Control Board or the Texas Commission on Environmental Quality. Every question is original; none is taken from a certification exam, an official study guide or another prep provider.