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Unit conversions and pressure: California T3 water treatment 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. An industrial customer's meter, which registers in CCF, read 9887 and, 28 days later, 12813. What was the average use in gallons per day?

  1. A) 78,200 GPD
  2. B) 61,300,000 GPD
  3. C) 3,260 GPD
  4. D) 10,500 GPD
Show the answer and worked solution

Answer: A) 78,200 GPD

1. Use = 12813 − 9887 = 2926 CCF. 2. 1 CCF = 748 Gal [Sheet p.1, Units and Conversion Factors, row 6: "1 CCF = 748 Gal"]: 2926 × 748 = 2,188,648 gal. 3. GPD = 2,188,648 gal ÷ 28 days = 78,166 GPD. 4. Answer: 78,200 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 16.3 MGD. What is this flow in cubic feet per second (CFS)?

  1. A) 122 CFS
  2. B) 25.3 CFS
  3. C) 1,510 CFS
  4. D) 189 CFS
Show the answer and worked solution

Answer: B) 25.3 CFS

1. 1 MGD = 1.55 CFS [Sheet p.1, Units and Conversion Factors, row 28: "1 MGD = 1.55 CFS"]. 2. CFS = 16.3 MGD × 1.55 = 25.265 CFS. 3. Answer: 25.3 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 25.2 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 pressure gauge is mounted 6.5 ft above the floor of a storage tank and reads 11.5 psi. How deep is the water in the tank, measured from the floor?

  1. A) 66.2 ft
  2. B) 20.1 ft
  3. C) 26.6 ft
  4. D) 33.1 ft
Show the answer and worked solution

Answer: D) 33.1 ft

1. 1 PSI = 2.31 Ft [Sheet p.1, Units and Conversion Factors, row 31: "1 PSI = 2.31 Ft"]: water above the gauge = 11.5 × 2.31 = 26.565 ft. 2. Add the gauge height: 26.565 + 6.5 = 33.065 ft. 3. Answer: 33.1 ft (rounded to 3 significant figures).

Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 31: "1 PSI = 2.31 Ft"

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