When I was much younger and didn't need to sleep
a lot I joined up with a group of guys who renovated
homes and sold them for a profit. I've probably
installed three or four hundred toilets, so I thought
I could help a friend with his leaky toilet. This is
not your plain white $69.95 piece of junk. My
friend's master bath cost a small fortune. The sink,
toilet, floor tile, and shower are all color matched.
Here's the problem. A small amount of clean water
was oozing out from the bottom front edge of the
caulk that seals the bowl to the floor tile. I could
not find any visible cracks in the bowl. I decided
to try using a bright orange dye. I dumped out
the cleanser from one of those bottles that people
hang inside their tanks. As the water level rises
and falls in the tank some of the cleanser is released
from the bottle. It's suppose to keep the bowl clean.
(It doesn't work, of course!) I mixed the orange
dye with water and filled the bottle. I told my friend
to call me again after the toilet had been flushed
a few dozen times. Maybe we could spot some
of dye on the outside of the bowl if there was a
hairline crack. We found nothing.
I pulled the toilet and flipped the bowl upsidedown.
Again, the bottom of the bowl looked very good.
The only thing left on the list that could cause a
leak was the wax ring or the floor flange. Because
I was in the home renovation business for several
years, I've seen plumbers use every trick in the
book to assure that a bowl mounted to an uneven
floor will not leak. They use double or triple wax
rings, or they take several pounds of plumber's
putty and create a donut around the bowl horn. The
idea is to seal the bowl so completely that it could
never leak. I've seen these "tricks of the trade" fail
too many times.
I thought I had died and gone to heaven when a company
called Fernco developed a flexible rubber connector that
always makes a leakproof connection between the bowl
horn and the floor drain. All the problems of uneven bath-
room floors, damaged flanges, etc., are irrelevant with this
ingenuous flexible connector. For a 3" drain pipe you buy
Fernco #FTS-3B. I've used it at least a dozen times with
My friend's very fancy and costly toilet is still leaking. This
problem is a real mystery! The water that oozes from the
bottom of the bowl is never more than an ounce or two. It
is not continuous. Weeks can pass with no leaking at all!
Once the leaking starts it usually continues for several days.
A plumber would have no patience with a problem of this sort.
Naturally, he would suggest junking the toilet. I asked
my friend to contact the factory and find out if he can get
an exact replacement. His wife would be very angry if we
installed a new toilet that did not match the rest of their
I hope someone can think of something I haven't tried.
I can only think of two things that might be causing this.
The first is the seal at the bottom. Have you tried one of the
new waxless seals that take the place of the wax rings ? That's
all I would ever use. You have to make sure that it seals properly in
the PVC that it was designed for--must go inside. I use the ultra seal
brand and they have a detailed instruction guide on their site.
The second is not that common. If the temperature of the water going
down has a spread (difference) of the outside temperature (dewpoint)
then it might be sweating on the inside. I know this usually happens on
the tank but this is a possibility. I once saw someone solve this
problem by stuffing insulation inside the bottom open spaces.
All this assuming there is no crack which you seem to have ruled out.
h email@example.com wrote:
Prop the john up onto a box or platform, fill and look for leaks. It will
be out of commission for a day but this should settle any questions. You
may need to connect a water source in case there is any relationship.
Unlikely but plausable: Water is leaking from the bottom of the tank seal
and running along the outside surface and draining into the bolt hole.
Condensation on the outside of the tank is doing the same. Poor venting or
partially clogged drain occasionally allows water to stand against the wax
ring inside the drain.
Likely: A hairline crack is concieled and occasionally opens or closes due
to the weight or position of the user. Clean water indicates it might be in
the path to the ring of holes under the rim. Dye might be too dilute to
see. Try UV dye and UV lamp. Much of the water that flows here does not
sit in the tank first.
replace the bottom of the toilet, the commode bowl.
or run a lighted toilet cam thru the base and look for a cracked trap
internal to the toilet. you've covered everything else.
other factors related to the crack leakage include temperatures and
weight of occupant or visiting occupant.
other toilet stuff for others at:
I'm no toilet expert, but a fairly good detective. How about filling
bowl and tank, separately, with vinegar and then testing pH of leak? Dye
probably too dilute to be sure. Can the drain have a minute crack, and
sewer back pressure cause leak occasionally?
We had odd behavior of one toilet before the whole sewer pipe for our
condo backed up into our condo, it being between sewer main and all
other units. A gurgle once in a while, for few days, then bath #1
toilet with puddle around base. Toilet #1 won't flush, so used toilet
#2, it backed up and ran over. Obviously, our toilets didn't decide to
plug up at the same time, must be sewer line. Called city (Sunday
evening, of course) to see if any reports of trouble downline, as the
area has long history of sewer problems and recent replacement of a pump
downline. Nope, says the city. Call plumber, rotoroots out all the way
to city main. Replaces wax seal and adapter thingamajig on our toilet
#1. About a week later, the city is digging up sewer directly across
the street from our condo. Seems to me that the city main plugged and
backup pressure or pressure from other units in condo blew the seal on
our toilet #1.
I really appreciate all your thoughtful replies!
Joey, I have tried some of the waxless seals.
I suppose the most popular ones are made
by Fluidmaster, since they have a virtual
monopoly in Home Depot and Lowes.
Here's why I'm completely sold on Fernco's
flexible horn to drain connector. As long as
the bottom of the bowl is smooth and clean
the connector bonds to the bowl flawlessly.
It uses an elastomeric adhesive that is
incredibly strong and very flexible. You can
lift the bowl off the floor by the connector
five minutes after you press it on!
The Fernco connector has two flexible ribs that
lock firmly inside the drain pipe. If the bowl is
not close to the wall you can literally spin the bowl
around in circle and not break the seal! Try that
with any other type of seal and you'll end up with
a flooded bathroom. Just to prove to myself that
this connector would never leak, I once shoved a
block of wood under one side of the bowl so that
the entire bowl was tilted and the connector was
not fully pushed down into the drain pipe. I took
a garden hose and ran thirty or fourty gallons of
water through the bowl. That Fernco connector
still did the job, even though I did everything I could
to screw it up!
By the way, I have no relationship whatsoever with
Thanks again guys. I'll give some thought to all your
If the vent is blocked, it should be showing signs regularly, shouldn't
it? Running slow or gurgling? All seems normal and this was about a
year ago. How does one check the sewer vent in 2 story building?
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