Maintenance Technician 2025 Complete Practice Test

The type of copper tubing that has the thinnest walls is indeed the type known as DWV (Drain, Waste, and Vent). DWV copper tubing is specifically designed for drainage applications and is manufactured with thinner walls compared to other types. This makes it suitable for gravity drainage systems where high pressures are not common, allowing it to be more cost-effective while fulfilling its purpose.

In contrast, Type M and Type L copper tubing have thicker walls, providing greater strength and durability that are often required in potable water systems and other applications that may involve higher pressure. Type M is typically used for lower-pressure applications, while Type L is suitable for higher-pressure installations. Type N, on the other hand, is not a standard designation in copper tubing but rather may pertain to a different classification not commonly used in residential plumbing.

Thus, the choice of DWV reflects its specific use case requiring thinner walls, making it the correct answer for this question.