How should drainage pipes be tested to ensure proper functionality?

Testing drainage pipes is crucial to ensure that they function properly and are free from leaks or obstructions. The most effective method mentioned in the options is to test drainage pipes with water at a 10-foot head or air at 5 psi. This approach allows plumbers to verify that the pipes can withstand the typical operational pressures they will encounter during regular use.

Using water allows for a direct assessment of how the system will perform under real conditions, as water is the typical medium these pipes will carry. A 10-foot head of water exerts a specific pressure that simulates real-world scenarios and enables the detection of leaks, weaknesses, or improper connections effectively. On the other hand, using air at a 5 psi pressure is also a standard practice that can quickly demonstrate whether there are any leaks in a system.

In contrast, while gas pressure, vacuum tests, or chemical solutions may have their places in plumbing, they are not the standard methods for testing drainage pipes. Gas pressure is not applicable for a drainage system as it poses safety risks and doesn't provide relevant information about the drainage capabilities of pipes. Vacuum tests can be helpful in specific applications but are often less comprehensive than the water or air tests mentioned. Chemical solutions could potentially damage the piping material and are not