Which of the following is a common tool used to check for leaks in plumbing?

A pressure gauge is commonly used to check for leaks in plumbing systems because it measures the pressure within pipes. When a plumbing system is pressurized, and there is a leak, the pressure will typically decrease over time. By monitoring the pressure readings on the gauge, a plumber can determine if there is a leak present based on unexpected drops in pressure. This tool is essential for ensuring the integrity of plumbing systems, particularly in situations involving water supply lines or gas lines, where maintaining the appropriate pressure is crucial for safety and functionality.

Other tools listed, such as a hammer, level, and wrench, serve different purposes in plumbing. A hammer is generally used for driving nails or securing components, a level is used to ensure that surfaces are even and properly installed, and a wrench is used for tightening or loosening nuts and bolts. While all these tools are important in various plumbing tasks, they are not specifically designed for leak detection like a pressure gauge.