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Unit conversions and pressure: California D3 water distribution operator math

Flow, volume, pressure/head and concentration conversions; meters; SCADA signals.

Below are 3 worked examples. Each answer is computed with the formulas and constants on the CA Exam Conversion Sheet (revised 4/30/2026), and the solution names the line it uses.

Formulas from the sheet for this topic

Example 1. A commercial customer's meter, which registers in CCF, read 79531 and, 29 days later, 79781. What was the average use in gallons per day?

  1. A) 3,230 GPD
  2. B) 6,450 GPD
  3. C) 269 GPD
  4. D) 862 GPD
Show the answer and worked solution

Answer: B) 6,450 GPD

1. Use = 79781 − 79531 = 250 CCF. 2. 1 CCF = 748 Gal [Sheet p.1, Units and Conversion Factors, row 6: "1 CCF = 748 Gal"]: 250 × 748 = 187,000 gal. 3. GPD = 187,000 gal ÷ 29 days = 6,448 GPD. 4. Answer: 6,450 GPD (rounded to 3 significant figures).

Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 6: "1 CCF = 748 Gal"

Example 2. A transmission main carries 5.5 MGD. What is this flow in cubic feet per second (CFS)?

  1. A) 41.1 CFS
  2. B) 8.53 CFS
  3. C) 511 CFS
  4. D) 3.55 CFS
Show the answer and worked solution

Answer: B) 8.53 CFS

1. 1 MGD = 1.55 CFS [Sheet p.1, Units and Conversion Factors, row 28: "1 MGD = 1.55 CFS"]. 2. CFS = 5.5 MGD × 1.55 = 8.525 CFS. 3. Answer: 8.53 CFS (rounded to 3 significant figures). 4. If you used 694.4 GPM per MGD (Units row 29) and 448.8 GPM per CFS (row 7) instead of 1.55 CFS per MGD (row 28), you get 8.51 CFS. The sheet prints both factors, so either answer is right; pick the option closest to yours.

Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 28: "1 MGD = 1.55 CFS"

Example 3. A chlorine solution is 5.25% strength. What is its concentration in mg/L?

  1. A) 52,500 mg/L
  2. B) 26,300 mg/L
  3. C) 438,000 mg/L
  4. D) 105,000 mg/L
Show the answer and worked solution

Answer: A) 52,500 mg/L

1. 1 % = 10,000 mg/L [Sheet p.1, Units and Conversion Factors, row 1: "1 % = 10,000 mg/L"]. 2. 5.25% × 10,000 = 52,500 mg/L. 3. Answer: 52,500 mg/L.

Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 1: "1 % = 10,000 mg/L"

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