What can cause issues like noise, stagnant water, and leaks in plumbing systems?

Sagging pipes can lead to several issues in plumbing systems, making this the correct choice. When pipes sag, it creates low spots where water can accumulate instead of flowing smoothly through the system. This stagnant water can lead to a variety of problems, including odors, corrosion, and increased risk of leaks. Additionally, sagging pipes can produce noise due to water movement and pressure changes within the system. Furthermore, the unnatural bends or dips in sagging pipes may also lead to joint stress and eventual leaks, exacerbating plumbing issues.

In contrast, supported pipes are typically installed properly and maintained to minimize any such issues. Unattended water levels generally pertain to conditions related to tanks or reservoirs rather than the pipes themselves, making them less relevant in this context. Physical connections involve the junctions between pipes and fittings; while poor connections can cause leaks, they do not directly relate to the problems associated with the sagging of pipes.