Which tool is essential for checking water pressure in a plumbing system?

A pressure gauge is essential for checking water pressure in a plumbing system because it directly measures the force exerted by the water within the pipes, helping to determine whether the water pressure is adequate for the system's operation. Maintaining proper water pressure is crucial for efficient plumbing performance, as too high or too low pressure can lead to system malfunctions, leaks, or inefficient water flow.

In contrast, a pipe wrench is primarily used for gripping and turning pipes, a measuring tape is for measuring lengths and dimensions of materials, and a level is meant for ensuring that surfaces are even or vertical. None of these tools provide the specific function of measuring water pressure, which underscores why the pressure gauge is the correct choice for this task.