FIGURE A
Click Image to enlarge.
Q I live in a ranch home with
the washing machine and
toilet in adjoining rooms. When
the washing machine discharges
water, air comes bubbling up
through the toilet. Sometimes
the water level in the toilet will
drop, too. The washing machine
connects to the house sewer line
before the toilet does. What’s
going on, and what’s the fix?
Robert Fisher, Decatur, IL
A You’re seeing signs of poor
venting, that is, your drain
line is gasping for air. When you pour
liquid from a can, you’ll notice that it
doesn’t flow evenly unless you have a
second opening for air. The same
holds true for plumbing. As water
goes down a drain, air is needed to
equalize the pressure in the drain line.
This is the purpose of a venting system.
If the drain lines in your home
have poor venting (as in Figure A, for
example), water rushing down the
drains will pull water from nearby
P-traps. The drain in the toilet bowl is
basically a P-trap. If the problem just
started, it’s probably a blocked drain
or vent that needs to be “snaked” out.
And since the water in the toilet is
dropping and gurgling, it’s likely that
the problem is near that area.
Unfortunately, a clogged or missing
vent is tough to fix, since it usually
requires breaking into the walls to
examine the drain system. Unless you
have plumbing experience, this project
is best left to a professional.
