a part of horizontal drainage structures; they act as a water-intake and overflow component. Drainpipes are used in systems for closed drainage of farmland and structures, as well as in other specialized drainage systems (such as prevention and mine drainage).

Drainpipes are made of various materials: ceramic, asbestos cement, concrete, reinforced concrete, wood, plastic, and porous materials (plastic concrete, and lightweight aggregate glass). Ceramic drainpipes, which have uniform porosity (water absorption of 12-18 percent) and high corrosion resistance and durability, are the most common type. Drainpipes are manufactured in diameters of 25-250 mm and lengths of 333, 500, and 850 mm. Ceramic drainpipes are installed very close to one another, with gaps of 1.5-2.0 mm through which the water enters. Holes or slits are made in asbestos-cement, concrete, and reinforced-concrete pipes for the intake of water. In drainpipes made from porous materials, water enters through the walls of the pipes.

Ceramic drainpipes, like clay bricks, are molded in horizontal band presses by the individual method (one bar of pipe is cast at a time), in packets (simultaneous casting of several pipes, which are soldered together), or by the separate-packet method (several pipes are cast and are immediately divided into separate pieces). Asbestos-cement, concrete, reinforced-concrete, and plastic drainpipes, as well as pipes of porous materials, are manufactured with special machine tools and instruments. Drainpipes are installed by drainlayers (the so-called trenchless method). Special cranes are used to lay the pipes in trenches.