Where are indirect connections not permitted?

Indirect connections are not permitted in a crawlspace primarily due to concerns regarding contamination and sanitation. A crawlspace often has limited ventilation and can be prone to moisture, which increases the risk of harmful substances entering the water supply if an indirect connection were to exist there.

In contrast, the other locations listed can have different choices regarding indirect connections based on plumbing codes and guidance. For instance, water lines and drainage in a main building, roof, or garage can be designed with provisions to manage potential cross-contamination or drainage issues effectively.

Thus, the crawlspace's unique attributes make it a location where indirect connections could lead to serious sanitary problems, reinforcing the importance of adhering strictly to plumbing regulations in that area.