Red Seal Plumbing Practice Exam

What is the minimum size of water line required for single family dwellings?

1. 15 mm (1/2")

2. 20 mm (3/4")

3. 25 mm (1")

4. 32 mm (1 1/4")

The correct answer is: 20 mm (3/4")

The minimum size of water line required for single family dwellings is typically 20 mm or 3/4". This is because a 20 mm line is able to provide enough water pressure and flow for everyday household uses, such as showering, washing dishes, and doing laundry. Option A, 15 mm, is too small and may result in insufficient water pressure. Option C, 25 mm, is larger than necessary and may result in wasted water. Option D, 32 mm, is also larger than necessary and may be more expensive to install. Overall, 20 mm is the most practical and cost-effective size for a water line in a single family dwelling.