Copper drains were quite popular years ago. This was a very good style of drainage before pvc. It was easier to work
with than galvanized or cast-iron, and requires less heavy tools. It's actually the same process of pipe fitting as standard
soldering of water lines that we still use today. Copper drains have fallen out of favor, but they do still exist in
many homes today.
Copper is actually a fairly good pipe for drains. Two major problems we have these days are: firstly, cost. Copper
simply costs too much, and we have longer lasting, cheaper pvc now. The other problem that we have 50 or so years later, is
that a good amount of the copper that was put in years ago is now starting to reach the end of its lifespan. Copper
drain pipe has a thin wall, which in this environment can corrode over an extended period. Paper thin copper pipe is
not an uncommon sight, although there is still quite a bit of copper drain out there yet that can still provide
years of service.
Any copper drains that need to be repaired are generally replaced with pvc. The damaged section is cut out, and
rebuilt. The new pvc is connected to the copper by means of a fernco adapter(see the fernco section). Copper drain
lines have a thin wall to begin with, so the outside diameter of the pipe is smaller than that of pvc. This really only
presents a problem with 1 1/2 copper line. In this case, an 1 1/2 x 1 1/4 fernco works best. The 1 1/4 side fits
much better on the copper.
The picture above shows copper drain line connected to cast-iron. Depending on the amount of work you want to put
in, very often it is acceptable to cut the copper off close to the cast-iron, then use a fernco to run pvc up to the
fixtures. This will, however, leave a small piece of copper drain in use, that could cause problems in the future.
As is the case with a lot of plumbing repairs, there is an element of chance. How much pipe should be replaced?
Sometimes questions like that can be very difficult to answer, even for a trained, experienced plumber.