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Unit conversions and pressure: California D1 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.

Example 1. A well pump runs continuously at 1,125 GPM. What is this flow in MGD?

  1. A) 0.0675 MGD
  2. B) 0.781 MGD
  3. C) 2.51 MGD
  4. D) 1.62 MGD
Show the answer and worked solution

Answer: D) 1.62 MGD

1. 1 MGD = 694.4 GPM [Sheet p.1, Units and Conversion Factors, row 29: "1 MGD = 694.4 GPM"]. 2. MGD = 1,125 GPM ÷ 694.4 GPM/MGD = 1.62 MGD. 3. Answer: 1.62 MGD (rounded to 3 significant figures).

Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 29: "1 MGD = 694.4 GPM"

Example 2. A hardness test reports 7 grains per gallon (gpg). What is the hardness in mg/L?

  1. A) 120 mg/L
  2. B) 240 mg/L
  3. C) 0.409 mg/L
  4. D) 58.4 mg/L
Show the answer and worked solution

Answer: A) 120 mg/L

1. 1 gpg = 17.1 mg/L [Sheet p.1, Units and Conversion Factors, row 18: "1 gpg = 17.1 mg/L"]. 2. Hardness = 7 × 17.1 = 119.7 mg/L. 3. Answer: 120 mg/L (rounded to 3 significant figures).

Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 18: "1 gpg = 17.1 mg/L"

Example 3. A hardness test reports 10.5 grains per gallon (gpg). What is the hardness in mg/L?

  1. A) 180 mg/L
  2. B) 0.614 mg/L
  3. C) 360 mg/L
  4. D) 87.6 mg/L
Show the answer and worked solution

Answer: A) 180 mg/L

1. 1 gpg = 17.1 mg/L [Sheet p.1, Units and Conversion Factors, row 18: "1 gpg = 17.1 mg/L"]. 2. Hardness = 10.5 × 17.1 = 179.55 mg/L. 3. Answer: 180 mg/L (rounded to 3 significant figures).

Source: CA Exam Conversion Sheet (Revised 4/30/2026), p.1, Units and Conversion Factors, row 18: "1 gpg = 17.1 mg/L"

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Practice all 250 unit conversions and pressure problems for CA D1 Math

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