ABSTRACT
CPT is manufactured from high-density polyethylene
(HDPE) or polyvinyl chloride (PVC). HDPE is common in
the United States and PVC is common in Europe.[3] Some
PVC pipes are manufactured as smooth wall pipes with
holes for water entry, but these are more commonly used
for drain fields for septic systems. The holes are usually
arranged as two rows various distances apart, various hole
diameters, and various distances between the holes. For
drainage the holes are placed on the bottom of the trench.
Because they are smooth walled, the wall thickness is
greater than CPT for proper strength. The length of these
pipes varies but is usually between 10 and 20 feet. CPT is
available in many different colors and may be formulated
with chemicals that retard ultraviolet (UV) light degrada-
tion (a problem with outdoor storage) or to prevent iron
ocher formation. (Iron ocher is a complex material of iron
bacteria, organic matter, and other materials that forms as a
sludge in the pipe and can seriously impede flow and
capacity of the pipe.)
