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Plumber Red Seal · Question

What is the minimum air gap required for a potable water supply to a fixture in an indirect waste arrangement?

The minimum air gap required is typically 25 mm (1 inch) or twice the diameter of the water supply pipe, whichever is greater, to provide adequate backflow prev

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Question: What is the minimum air gap required for a potable water supply to a fixture in an indirect waste arrangement?

Answer options:

  • 1 inch (25 mm) or twice the diameter of the supply pipe (whichever is greater) ✅ 2 inches (50 mm) or twice the diameter of the supply pipe (whichever is greater)
  • 1 inch (25 mm) or the diameter of the supply pipe (whichever is greater)
  • 2 inches (50 mm) or the diameter of the supply pipe (whichever is greater)

Correct answer: 2 inches (50 mm) or twice the diameter of the supply pipe (whichever is greater)

Explanation: The minimum air gap required is typically 25 mm (1 inch) or twice the diameter of the water supply pipe, whichever is greater, to provide adequate backflow prevention. Some applications specify 50 mm (2 inches).

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