What type of installation is commonly referred to when pipes are run horizontally in drainage systems?

The term "sloping installation" refers to the practice of running pipes at a slight angle, typically downward, to facilitate the flow of drainage. This type of installation is crucial in drainage systems as it helps prevent the stagnation of water and ensures that waste and effluent flow smoothly towards the discharge point. Proper slope is essential to maintain the gravity flow principle, which is fundamental to the effectiveness of plumbing systems.

In various contexts, sloping installations can also relate to the recommended angles for effective drainage, such as a slope of 1/4 inch per foot for pipes carrying wastewater. This alignment assists in combating potential issues such as blockages and backups, which can arise when horizontal pipes are not installed with the right slope.

Other terms in the options do not specifically address this necessity for proper drainage flow, making "sloping installation" the accurate description for horizontally run pipes in a drainage context.