Water operator math practice, solved step by step
Free math practice for the Texas Class D water exam: tank volume, chemical dosage, flow conversions, and pressure. Work each one on paper, then watch it solved one small step at a time, with a plain-words explanation under every step. Built for people who have been out of school a while.
Water math topics
Tank volume in gallons
Rectangular and round tanks: get the cubic feet, then multiply by 7.48 for gallons.
Practice itChemical dosage (pounds per day)
The pounds formula: flow in MGD times dose in mg/L times 8.34.
Practice itFlow conversions
Move between GPM, GPD, and MGD using 1,440 minutes in a day.
Practice itPressure and head
Turn feet of water into psi with 0.433, and psi back into feet with 2.31.
Practice itEvery practice problem
Work it on paper, then watch it solved one small step at a time.
- Water & wastewaterHow much pressure does 92 feet of water make?Try it, then watch
- Water & wastewaterHow many gallons are in a 20 by 10 by 8 foot tank?Try it, then watch
- WaterHow many gallons are in a 30 foot round tank?Try it, then watch
- Water & wastewaterHow many pounds of chlorine for 2 MGD at 3 mg/L?Try it, then watch
- Water & wastewaterHow do you turn 350 GPM into gallons per day?Try it, then watch
- Water & wastewaterWhat is the area of a 40 by 12 foot clarifier?Try it, then watch
- Water & wastewaterWhat is the flow if 6,000 gallons fill in 30 minutes?Try it, then watch
- Water & wastewaterHow many GPM is 1.44 MGD?Try it, then watch
- Water & wastewaterHow much does 500 gallons of water weigh?Try it, then watch
- Water & wastewaterHow many gallons are in 2,000 cubic feet?Try it, then watch
- Water & wastewaterWhat is the detention time in minutes for 5,000 gallons at 250 GPM?Try it, then watch
- Water & wastewaterHow many feet of head is 50 psi?Try it, then watch
- Water & wastewaterWhat percent of capacity is 400 GPM out of 500?Try it, then watch
Keep practicing
All practice problems
The full set of worked problems for both tracks, solved step by step.
The math method, solved simply
The plain-language method behind each formula, worked the simplest way.
Free operator calculators
Plug in your own numbers for volume, dose, flow, and pump run time.
Free practice tests
Ready to test yourself once the method feels solid.
Common questions
- What math is on the Texas Class D water operator exam?
- Unit conversions, area and volume, chemical dosage, and flow. It is closed-book, but you are given a formula and conversion sheet, so the skill is knowing when to use each formula, not memorizing numbers.
- Are these real exam questions?
- No. Every problem is original teaching material written to practice the same math the exam uses. Nothing here predicts your official score.
- Is the water math practice free?
- Yes. Every worked problem is free, with the full step-by-step walkthrough and a plain-words explanation.
- What are the key water constants to remember?
- 7.48 gallons per cubic foot, 8.34 pounds per gallon, 0.785 for a circle, and 0.433 psi per foot of water. Each shows up again and again.