Sink Trap and Drain Q&A
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Dear NH,
The pipe that connects to my bathroom sink drain has come
undone. The drain also came loose in the sink, which I repaired
with plumber's putty (yeah!).
I noticed that under the other bathroom sinks the piping comes
out of the wall and then is turned about 30 degrees, whereas the
pipes to the broken sink are straight. I'm not sure how this
happened (no one will confess). Could this be why the pipe won't
stay compressed against the drain? All of the fittings seem to fit
tight.
A plumber told me I need a longer pipe (I'm assuming that means
the straight one that comes down from the drain). I noticed that
the small straight pipe can be lengthened, but I was unable to
make it stay tight against the drain opening. I'm assuming I need
to loosen the connectors and turn the larger black pipes to a 30
degree angle like the others. All of the washers seem to be in
good condition. As you can tell, I'm plumbing illiterate but don't
want to pay a plumber for something that I'm guessing could be
easily fixed. Any help is appreciated!
LN from Fresno, CA
LN,
Because drain fittings use somewhat flexible washers... either
rubber or plastic... to seal the joints, there is some allowance
for "crookedness" in the connections. However, there is
a point where seepage will occur so it may be wise to try to
straighten them as much as possible.
In my experience, one of the biggest mistakes made by
do-it-yourselfers when cutting drain pipe under sinks is either
cutting the pipes too long or cutting them too short. Overly long
pipes will force the trap assembly out of alignment and put
unnecessary stress on all connections.
Cutting the pipes too short can be a silent killer... even
though the connection seems water tight, over time leaks can
start. A good knock with a bottle of mouthwash can cause a
too-short tailpiece (the vertical pipe beneath the strainer) to
dislodge from the trap, leading to a disastrous leak! A good rule
of thumb is to cut the pipe so that at least an inch of pipe
extends beyond the connection's washer. You'll get plenty of
strength with no binding.
You didn't say whether or not you are trying to work with old
or new parts. My suggestion is that IF you are trying to stop a
leak it is usually better to purchase new parts once you get the
assembly apart than to reuse the old ones. The only exception
would be if the drain assembly is fairly new and corrosion-free.
There are some special-situation plastic drainpipes that are
designed to "flex" so you have a little more wiggle room
if the original plumbing is out of whack! One of these might help
you get things back into "whack"!
As a final suggestion, when assembling a sink drain, always
keep all connections threaded but loosely fit until you have all
parts properly aligned. Then begin to tighten them. A small amount
of plumber's grease on the threads only will make tightening a
little more effortless and more effective.
NH
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