Wastewater Operator Test Prep
Certification Math Calculator
Free · Designed for iPad. Not verified for macOS.
Studying for your wastewater operator certification exam? Practice with real exam-style questions, then master the math — the section where most candidates lose points.
PRACTICE MODE
Hundreds of original practice questions covering Class I through Class IV, weighted across content areas the way the real certification exams are: treatment process, equipment and maintenance, laboratory, and safety and regulations. Math word problems are freshly generated every quiz with realistic plant values, and every answer comes with a worked, step-by-step solution. Pick your session — a 10-question quick quiz, a 25-question study session, or a full 100-question exam-length run — filter by certification class, and drill just math or just concepts when you want to. Wrong answers are modeled on the classic mistakes — the dropped 8.34, the inverted ratio — so the quiz teaches you what to watch for.
50 CALCULATORS
The full certification exam formula sheet, Class I through Class IV. Every result shows the formula with your values substituted in, exactly the way you'd show your work on the exam. Practice until the math is automatic, then keep the app in your pocket for daily process control once you're licensed.
SHOW YOUR WORK
Tap any result to see your actual inputs plugged into the equation — dose, flow, and conversion factors spelled out step by step. Verify the math instead of trusting a black box.
HYDRAULICS & LOADING
• Pounds / Mass Loading (MGD, GPD, or GPM input)
• Detention Time
• Percent Removal
• Surface Overflow Rate and Weir Overflow Rate
• Rectangular and Circular Tank Volume
• Pipe Velocity, Channel Flow (Q = A × V), Float Test Velocity
• Hydraulic Loading, Total Flow from Meter Readings
CHEMICAL DOSING
• Chemical Dose / Feed Rate (dry and liquid with SG)
• Chlorine Demand
• Hypochlorite Feed Rate
• Solution Strength
• Alkalinity for Nitrification
SOLIDS CONTROL
• Sludge Volume Index (SVI)
• RAS Rate, RAS Pump Rate, RAS Solids Balance
• MLSS / MLVSS Inventory
• WAS Flow Required
• Sludge Volume Pumped, Dry Pounds Pumped, Solids Recovery
PROCESS CONTROL
• Sludge Age and full MCRT / SRT
• F/M Ratio
• Solids Loading Rate
• OUR / SOUR
• Volatile Solids Reduction (Van Kleeck)
• Digester Loading, Trickling Filter Organic Loading
PUMPING & HORSEPOWER
• Water, Brake, and Motor Horsepower
• Wire-to-Water Efficiency
• Power Cost
• Pumping Rate, Wet Well Drawdown, Total Dynamic Head
LAB & SAMPLING
• BOD (Dilution Method)
• Total Suspended Solids
• Percent Volatile Solids
UNIT CONVERSIONS
• Flow (MGD, GPM, GPD, cfs)
• Volume (gallons, liters, cubic feet, acre-feet)
• Pressure to Head, Power, Temperature
BUILT FOR THE FIELD
• Works 100% offline — study anywhere, calculate anywhere
• Large, readable results designed for gloved hands
• Copy Result pastes a formatted summary, math included, ready for texts or emails
• Formula reference screen with source attribution for every equation
• Calculation history saves your last 20 results
• Dark mode support
ACCESSIBILITY
• Full VoiceOver support — every input, button, and result is labeled
• High contrast dark mode with OLED-friendly true black
• Large touch targets sized for field use
Formulas follow the ABC formula sheet and Sacramento State OIT course materials — the same references most state certification exams draw from. Independent study tool — not affiliated with ABC, AWWA, or any certification board.
Built by Product Party for wastewater professionals.
Ratings & Reviews
Stability improvements. After you copy a result or pass a practice session, you may see a request to rate the app. Ratings help other operators find it.
The developer, Mike Watson, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Mike Watson
- Size
- 29.5 MB
- Category
- Education
- Compatibility
Requires iOS 15.1 or later.
- iPhone
Requires iOS 15.1 or later. - iPad
Requires iPadOS 15.1 or later. - iPod touch
Requires iOS 15.1 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Mike Watson