Cleanouts for drainage pipes should be installed _____________ apart in horizontal drainage lines measured from the upstream entrance of the cleanout.

In plumbing systems, cleanouts are essential access points that allow for the maintenance and cleaning of drainage pipes. The correct distance for the installation of cleanouts in horizontal drainage lines, measured from the upstream entrance of the cleanout, is 100 feet. This guideline is important to ensure that blockages can be adequately addressed without having to dig up extensive lengths of drainage piping.

The 100-foot spacing allows for efficient access to the drainage system, ensuring that clogs can be tackled effectively at reasonable intervals. This requirement also ensures compliance with plumbing codes, which specify cleanout locations to enhance the overall maintenance of the plumbing system.

By following this guideline, plumbers help ensure the system remains functional and reduces the risk of significant issues arising due to unnoticed blockages over long sections of the pipeline. Proper planning around cleanout installation enhances both the efficiency and longevity of drainage systems.