Study guide · Texas Class D Water
Study the Class D water exam, subject by subject
The Class D water exam is built from eight official TCEQ subjects. Here is what to know in each, in plain language, with one-tap practice to drill it. Study a subject, practice it, move to the next. Most of the exam is knowledge, not math.
Rules and regulations
The rules that govern a public water system and the operator's legal duties under them: who the TCEQ is, what a public water system must do, and the monitoring, sampling, and reporting an operator is responsible for. This is knowledge, not math, and a large share of the exam.
What to nail. Know the operator's responsibilities and the reporting duties, not every rule number. Understand why the rules exist: to keep the water safe.
Drill:rules and regulationsGeneral water knowledge
The foundation: what a public water system is, how water moves from source to tap, the roles at a small system, and the plain vocabulary the rest of the exam assumes you already know.
What to nail. Get the vocabulary and the source-to-tap path automatic so the harder subjects make sense.
Drill:general water knowledgeGroundwater sources
Where groundwater comes from and how a system that draws on it is run: wells and aquifers, groundwater under the influence of surface water, and why most groundwater systems can be treated more simply than surface water.
What to nail. Know how a well and aquifer work and when groundwater has to be treated like surface water.
Drill:groundwater sourcesSurface water sources
Rivers, lakes, and reservoirs as a source, and why surface water needs more treatment than groundwater: it carries more particles and organisms, so turbidity, filtration, and disinfection matter more.
What to nail. Understand why surface water is harder to treat, and the role of turbidity and filtration.
Drill:surface water sourcesStorage and distribution
How treated water is stored and delivered under pressure: storage tanks, keeping pressure up across the distribution system, protecting against backflow and cross-connections, and holding a disinfectant residual all the way to the customer.
What to nail. Know why pressure and a disinfectant residual keep distributed water safe, and what a cross-connection is.
Drill:storage and distributionDisinfection
How a system kills or inactivates organisms so the water is safe to drink: chlorination, the difference between dose, demand, and residual, contact time, and the monitoring that proves disinfection is working.
What to nail. Nail dose, demand, and residual and why contact time matters. Some of this crosses into the math subject.
Drill:disinfectionOperator safety
Keeping the operator safe on the job: handling chlorine and other chemicals, confined-space hazards, personal protective equipment, and the everyday practices that prevent injury at a water system.
What to nail. Know the main hazards, especially chlorine and confined spaces, and the basic precautions for each.
Drill:operator safetyOperator math
The calculating the exam asks for: unit conversions, tank volume, flow, and simple chlorine dosage, using constants like 7.48 gallons per cubic foot, 8.34 pounds per gallon, and 0.785 for circles. It is a smaller share of the exam than the knowledge subjects, and a non-programmable calculator is allowed.
What to nail. Drill the handful of formulas and constants until setup is automatic. The free calculators show every step.
Drill:operator math
How to use this
Start with the part your diagnostic flagged as weakest, not the first one on the list. Read the overview, drill it until it is steady, then move to the next weakest. Even, steady coverage of the whole exam is the honest finish line.