Answered
What is on the Texas Class D water exam?
The Texas Class D water exam is built from the official TCEQ Need-to-Know subjects: water sources and treatment, disinfection, distribution and storage, monitoring and sampling, safety, regulations, and basic operator math. It is closed-book, and you need 70 percent to pass. Every question comes from that published scope.
Last reviewed 2026-08-03
The subjects
Most of the exam is operational knowledge, how a public water system is treated, disinfected, stored, distributed, monitored, and kept safe, plus the regulations that govern it. A smaller share is basic operator math.
Why the scope matters
The exam draws only from the published TCEQ Need-to-Know. Studying higher-grade or out-of-state material adds topics you will not be tested on and wastes your time. Practice the exact scope instead.
Common questions
- Is it mostly math?
- No. Most questions are operational knowledge; a smaller share is basic math.
- Is it closed-book?
- Yes.
- What score passes?
- A minimum of 70 percent.