Which condition is NOT recommended for the installation of a trap in domestic plumbing systems?

Using bell traps is not recommended for the installation of traps in domestic plumbing systems because they are considered outdated and inefficient compared to other trap designs. Bell traps can trap solids and debris, leading to clogs and requiring frequent maintenance. Modern plumbing codes typically promote the use of more effective traps, such as P-traps or S-traps, which provide a better seal against sewer gases while allowing for easier maintenance and cleaner drainage.

On the other hand, providing cleanout access, ensuring proper depth of trap seal, and maintaining a sloped drain line are essential best practices in plumbing. Cleanout access allows for easy servicing and clearing of blockages, while a proper depth of trap seal is critical to prevent sewer gases from escaping into the home. Maintaining a sloped drain line ensures effective gravity drainage, minimizing the risk of stagnant water and potential backups. These principles support the functionality and reliability of plumbing systems, which is why they are emphasized in plumbing codes.