Massachusetts Plumbers Journeyman Practice Exam

What is the minimum nominal pipe diameter required for a water service main to a residence according to the text?

1. 1 inch

2. 1 ¼ inches

3. ½ inch

4. ¾ inch

The correct answer is: ¾ inch

The minimum nominal pipe diameter required for a water service main to a residence is typically ¾ inch. This size is generally considered adequate to supply water to most residential fixtures while maintaining appropriate water pressure and flow. The ¾ inch diameter is a standard size that strikes a balance between ensuring sufficient water delivery and accommodating various plumbing needs without unnecessary costs or excess material. Larger diameters, such as 1 inch or 1 ¼ inches, may be used in specific situations where higher water demands are expected, but they are not the minimum requirement for typical residential installations. A smaller diameter like ½ inch is often insufficient for effective water service in a residence, as it may restrict flow and pressure, leading to inadequate performance for daily water usage needs. Hence, the ¾ inch size is the minimum specified for effective residential water service.