Exam math · Foundations
The conversion backbone
The handful of conversions nearly every problem passes through.
The formula
7.48 gallons per cubic foot; 8.34 pounds per gallon of water; 1,440 minutes per day; one MGD is about 694 gallons per minute; one percent is 10,000 mg/L.
The unit trap
The formula sheet lists conversions but does not perform them. Practicing conversions cold, on paper, is the single highest-yield hour in operator math prep.
Worked practice example
Practice flow of 1,388 gallons per minute is 1,388 / 694, almost exactly 2 MGD. (Invented numbers.)
On exam day
A formula and conversion table is provided with the standardized exam; the official version is published by the exam provider at gowpi.org. These pages teach the concepts in our own words so the sheet on the desk reads as a reminder, not a puzzle.
The rest of the math
| Volumes | Tank volume |
| Volumes | Pipe and cylinder volume |
| Flow | Flow and velocity |
| Flow | Detention time |
| Treatment math | Chemical dosage |
| Treatment math | Percent strength and dilution |
| Treatment math | Removal efficiency |
| Hydraulics | Pressure and head |
| Hydraulics | Pump and horsepower math |
| Foundations | Averages and loading rates |
| Foundations | The formula-first method |
The operator math sheet
One printable page: the exam format, the formula-first drill method, and the unit-conversion discipline that decides the math questions. Free.
No spam. One useful sheet and occasional notes.