Terracotta pipe is used in drain-waste-vent (DWV) plumbing systems and sewer sytems. It is one of the oldest pipe materials in the world, and is still around and in use. Terra-cotta, also known as terracotta, terra cotta or vitrified clay, is an unglazed baked ceramic. It was used by the ancient Romans as drain pipe, and some of these drains are still functioning today.
Although it is not used for new construction in typical modern buildings, it’s low cost and durability means it still turns up from time to time during remodeling or repair plumbing work. Old leaking drainpipe runs that need replacing or repairing are sometimes found to be terracotta, and will need to be replaced with iron or plastic pipe, or even repaired with fitting splices.
Terra-cotta Pipe Joints
In residential uses, terra cotta pipe sections had one spigot (male) end and one bell (female) end. Joints were made by inserting the spigot end into the bell end of an adjoining pipe and then packing mortar around it. Newer replacement terra cotta piping now comes from the manufacturer with a Calder coupling on one end. (A Calder coupling is a large rubber ring with stainless steel worm-drive clamps on each end)
Terracotta pipe has the thickest wall of all residential plumbing pipe materials, so in order to adapt it to join with other materials, a rubber bushing is added to the inside of the rubber coupling. You can obtain adapter bushings for terra cotta to copper, to iron and to plastic.
Terracotta piping comes in various diameters and lengths, but the most common is 4, 6 and 8 inch diameter. New terra-cotta is a yellow-orange or red-orange hue, but as it ages it turns a dark brown or olive green color, due to exposure to water and soil for years on end.
Terracotta of good quality is not susceptible to age deterioration, however, it cannot withstand flexing and shocks well, so it is only used in the soil where it can be fully supported, which rules out all interior applications.
New terra cotta pipe can be cut with a soil pip cutter tool relatively easily, and leaves a clean, razor sharp edge; use gloves and when protective eyewear. Older piping is harder to cut, since the inner third of the pipe becomes saturated with water and snaps off at a different rate than the dry portion. So instead of using a chain-type soil pipe cutter tool, if you need to cut excavated terracotta pipe for repair or replacement, it is better to use a reciprocating saw with a carborundum coated blade.