D2 water distribution math worksheet
California D2 water distribution operator exam · 10 problems
Name: ______________________________ Date: ______________
Use the CA Exam Conversion Sheet (revised 4/30/2026) and a calculator.
1. The water surface in a reservoir is 347 ft above a pressure gauge on a closed (static) main. What should the gauge read?
Unit conversions and pressure
- A) 113 psi
- B) 45.8 psi
- C) 150 psi
- D) 75.0 psi
2. A 4.8 MGD system is dosed at 3.5 mg/L with 15% sodium hypochlorite that weighs 10.3 lbs/gal. How many gallons of hypochlorite are fed per day?
Chlorination and CT
- A) 934 GPD
- B) 13.6 GPD
- C) 90.7 GPD
- D) 112 GPD
3. An 8-inch main carries 220 GPM. What is the velocity in ft/sec?
Flow, velocity and detention
- A) 0.705 ft/sec
- B) 1.41 ft/sec
- C) 0.351 ft/sec
- D) 0.937 ft/sec
4. A round steel reservoir is 80 ft in diameter and 31 ft high. What is the surface area of the interior walls only (not the floor or roof)?
Area and volume
- A) 12,800 ft²
- B) 15,600 ft²
- C) 9,740 ft²
- D) 7,790 ft²
5. A well's pumping water level is 163 ft below ground and its drawdown is 128 ft. What was the static water level before pumping?
Wells, pumps and power
- A) 17.5 ft
- B) 128 ft
- C) 35.0 ft
- D) 291 ft
6. A flow transmitter is scaled 4 mA = 0 GPM and 20 mA = 1,800 GPM. The SCADA input reads 7.6 mA. What flow does that represent?
Unit conversions and pressure
- A) 405 GPM
- B) 540 GPM
- C) 684 GPM
- D) 855 GPM
7. A system treats 16.45 MGD with a chlorine dose of 4.9 mg/L. How many pounds of chlorine gas are fed per day?
Chlorination and CT
- A) 80.6 lbs/day
- B) 672 lbs/day
- C) 1,030 lbs/day
- D) 603 lbs/day
8. What is the capacity, in MGD, of a 4-inch main if velocity is limited to 6 ft/sec?
Flow, velocity and detention
- A) 0.169 MGD
- B) 0.338 MGD
- C) 0.113 MGD
- D) 0.254 MGD
9. A round steel reservoir is 25 ft in diameter and 26 ft high. What is the surface area of the interior walls only (not the floor or roof)?
Area and volume
- A) 491 ft²
- B) 2,530 ft²
- C) 1,020 ft²
- D) 2,040 ft²
10. A well's pumping water level is 285 ft below ground and its drawdown is 60 ft. What was the static water level before pumping?
Wells, pumps and power
- A) 225 ft
- B) 285 ft
- C) 345 ft
- D) 450 ft
Answer key: D2 water distribution math worksheet
1. C) 150 psi
1. 1 Ft (H₂O) = 0.433 PSI [Sheet p.1, Units and Conversion Factors, row 12: "1 Ft (H2O) = 0.433 PSI"]. 2. Pressure = 347 ft × 0.433 psi/ft = 150.251 psi. 3. Answer: 150 psi (rounded to 3 significant figures).
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 12: "1 Ft (H2O) = 0.433 PSI"
2. C) 90.7 GPD
1. Liquid (Gal) = MG × mg/L × 8.34 ÷ (Strength/100 × Chemical Weight) [Sheet p.1, Chlorination: "Liquid (Gal) = MG x mg/L x 8.34 / (Strength (%)/100 x Chemical Weight (lbs/gal))"]. 2. = 4.8 × 3.5 × 8.34 ÷ (0.15 × 10.3) = 140.112 ÷ 1.545 = 90.69 GPD. 3. Answer: 90.7 GPD (rounded to 3 significant figures).
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Chlorination: "Liquid (Gal) = MG x mg/L x 8.34 / (Strength (%)/100 x Chemical Weight (lbs/gal))"
3. B) 1.41 ft/sec
1. Q = 220 GPM ÷ 448.8 GPM/CFS = 0.4902 ft³/sec [Sheet p.1, Units and Conversion Factors, row 7: "1 CFS = 448.8 GPM"]. 2. A = .785 × (8 ÷ 12)² = 0.34889 ft² [Sheet p.1, Area and Volume: "Area of Circle = .785 X D2"]. 3. V = Q ÷ A [Sheet p.1, Flow & Velocity: "V (Ft/Sec) = Q (Ft3/Sec) / A (Ft2)"] = 0.4902 ÷ 0.34889 = 1.405 ft/sec. 4. Answer: 1.41 ft/sec (rounded to 3 significant figures).
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 7: "1 CFS = 448.8 GPM"; p.1, Area and Volume: "Area of Circle = .785 X D2"; p.1, Flow & Velocity: "V (Ft/Sec) = Q (Ft3/Sec) / A (Ft2)"
4. D) 7,790 ft²
1. Circumference = 3.14 × D [Sheet p.1, Area and Volume: "Circumference of a Circle = 3.14 x D"] = 3.14 × 80 = 251.2 ft. 2. Wall area = circumference × height [Sheet p.1, Area and Volume: "Area of Rectangle = Length x Width"] = 251.2 × 31 = 7,787.2 ft². 3. Answer: 7,790 ft² (rounded to 3 significant figures).
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Area and Volume: "Circumference of a Circle = 3.14 x D"; p.1, Area and Volume: "Area of Rectangle = Length x Width"
5. C) 35.0 ft
1. Drawdown = pumping water level − static water level (the denominator of [Sheet p.1, Pumping: "Specific Capacity (GPM/Ft) = Well Yield (GPM) / Drawdown (Ft)"]), so static water level = pumping water level − drawdown. 2. = 163 − 128 = 35 ft below ground. 3. Answer: 35.0 ft.
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Pumping: "Specific Capacity (GPM/Ft) = Well Yield (GPM) / Drawdown (Ft)"
6. A) 405 GPM
1. Process Units = (Live Signal − 4 mA) × Process Range ÷ 16 mA [Sheet p.1, Electrical/SCADA: "Process Units = (Live Signal (mA) - 4 mA) x Process Range / 16 mA"]. 2. (7.6 − 4) = 3.6 mA; 3.6 × 1,800 ÷ 16 = 405 GPM. 3. Answer: 405 GPM.
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Electrical/SCADA: "Process Units = (Live Signal (mA) - 4 mA) x Process Range / 16 mA"
7. B) 672 lbs/day
1. Gas (lbs) = MG × mg/L × 8.34 [Sheet p.1, Chlorination: "Gas (lbs) = MG x mg/L x 8.34"]; with MGD it gives lbs/day. 2. = 16.45 × 4.9 × 8.34 = 672.2 lbs/day. 3. Answer: 672 lbs/day (rounded to 3 significant figures).
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Chlorination: "Gas (lbs) = MG x mg/L x 8.34"
8. B) 0.338 MGD
1. A = .785 × (4 ÷ 12)² = 0.08722 ft² [Sheet p.1, Area and Volume: "Area of Circle = .785 X D2"]. 2. Q = A × V [Sheet p.1, Flow & Velocity: "(Q) Flow (Ft3/Sec) = (A) Area (Ft2) x (V) Velocity (Ft/Sec)"] = 0.08722 × 6 = 0.52332 ft³/sec. 3. 1 MGD = 1.55 CFS [Sheet p.1, Units and Conversion Factors, row 28: "1 MGD = 1.55 CFS"]: 0.52332 ÷ 1.55 = 0.3376 MGD. 4. Answer: 0.338 MGD (rounded to 3 significant figures).
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Area and Volume: "Area of Circle = .785 X D2"; p.1, Flow & Velocity: "(Q) Flow (Ft3/Sec) = (A) Area (Ft2) x (V) Velocity (Ft/Sec)"; p.1, Units and Conversion Factors, row 28: "1 MGD = 1.55 CFS"
9. D) 2,040 ft²
1. Circumference = 3.14 × D [Sheet p.1, Area and Volume: "Circumference of a Circle = 3.14 x D"] = 3.14 × 25 = 78.5 ft. 2. Wall area = circumference × height [Sheet p.1, Area and Volume: "Area of Rectangle = Length x Width"] = 78.5 × 26 = 2,041 ft². 3. Answer: 2,040 ft² (rounded to 3 significant figures).
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Area and Volume: "Circumference of a Circle = 3.14 x D"; p.1, Area and Volume: "Area of Rectangle = Length x Width"
10. A) 225 ft
1. Drawdown = pumping water level − static water level (the denominator of [Sheet p.1, Pumping: "Specific Capacity (GPM/Ft) = Well Yield (GPM) / Drawdown (Ft)"]), so static water level = pumping water level − drawdown. 2. = 285 − 60 = 225 ft below ground. 3. Answer: 225 ft.
Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Pumping: "Specific Capacity (GPM/Ft) = Well Yield (GPM) / Drawdown (Ft)"