Hi, I'm doing my first DWV system in a residence for myself. I have a
book on the subject and I'm sure I'm getting all the slopes a code
rules correct, but the book doesn't cover testing. I'm using PVC for
the vents but transition to hubless cast iron for the drains. I think
they like to use the "air test" for all-PVC systems around here.
Q1: Is there anything special I need to do to make the system testable?
Q2: How to I seal off a PVC outlet? I would assume you just leave a
stub and glue on a cap, which can then be sawn off after the test.
Q3: How to I seal off cast iron outlet?
Q4: What is a test tee?
Q5: What's the difference between test plugs and test caps?
I'm not a plumber, but my plumbing in my new addition just passed the pressure
test a few weeks ago.
Seal it tightly :-) Don't forget the roof vents.
That's the simplest way, otherwise, use a test plug. They fit into the end of a
specific size pipe and tighten up with a large wing nut. Be sure and get one
that is rated for enough pressure. If you buy Oatey plugs (Home Depot), the
metal ones are only rated for 2 psi, the plastic ones for 5+ psi (backwards of
what you might expect). Plumbing supply stores have the good ones.
Our inspector allowed me to leave the PVC-to-cast iron connector off, and I
used a 3" test plug on the PVC. When done, remove the test plug and connect
with a rubber coupling. Buy the torque driver to properly tighten them, they
are only about 10 bucks. Other wise use an inflatable test ball through a test
tee at that point.
Just a tee that is properly positioned to allow testing and cleanout.
If you are referring to the test caps that are rubber caps that fit *over* the
end of the pipe, the ones I found are not rated for use with air pressure.
Test plugs are as I described earlier.
There are also inflatable test plugs (or test balls) that fit further down into
the pipe and are inflated with a hose to seal the pipe where you can't
otherwise seal it. There are versions designed to fit into a test tee and seal
the main run, for instance. I needed one at the toilet since my closet bend did
not have a breakaway test cap.
You will also need to provide a connection for the air pressure, a shut off
valve to watch the pressure hold, and a gauge that remains on the pressurized
side when the air is shutoff.
Standard test is 5 psi for a specified length of time (may vary with the system
size). Our inspector wanted 30 minutes with no pressure drop on the gauge, test
beforehand before you call for the inspection.
If your system does not hold at first, you need to bubble check all the joints
to find the leak and repair it.
When we built our home (Aug 02 - Feb 04), I did all the plumbing myself.
For rough-in inspection, the stacks were not yet connected to the drains
in the basement.
All toilet flanges were ones that have a sealed hole that is knocked out
just before the toilets were installed. All sink drains and the vents
on the roof had rubber test plugs placed on them (the kind with a hose
clamp to make sure it stayed put).
There were two stack connections in the basement. Where they ended
pending the inspection, I made my own test caps by purchasing a 3" ABS
cap, a 0-30 PSI pressure gauge, and a valve like the type on a tire that
fits in a 1/4" thread. I drilled and tapped two 1/4" holes in the end of
the ABS caps and threaded a gauge and a valve on each. The cap was then
glued on the ends of the stacks. Each one cost a total of about $12 ($6
for the gauge, $2 for the valve, and $2 for the cap plus taxes).
Using a compressor with a tire-filling fitting on its hose, I filled each
stack to 5.1 PSI (our code requires the system to hold this pressure for
at least 30 minutes).
The inspector was impressed with my home-made test caps that he asked
if he could have one when I was done with them. Once cut off, one could
use a rubber couping to re-use it for other applications.
My guess, there are contractors out there who now loath him as he probably
uses this to make sure the pressure test is done properly! ;-)
Yea - or you could use the rubber test caps. Glueing a hard cap on and
cutting it off later is probably less expensive.
You are going to have to go with the rubber cap for that one.
I have not heard that term.
Those blue test caps are not for testing - they will blow off at about
2 PSI. Trust me, I know! ;-)
"I really think Canada should get over to Iraq as quickly as possible"
In my area, they allow air or water testing. Water testing is easier, but
if you do have a leak (or forgot to glue a fitting), you could
potentially end up with a mess... :)
In simple terms, seal off all open pipes (roof vents, sink drains, etc.)
then pressurize the system with water or air and inspect the system for
I used the glue-in PVC caps. They're only 20 cents or so, compared to a
few dollars for the rubber clamp on types. After the test, just pop out
the center with a hammer, and clean up the inside with a knife. You can
glue on whatever fitting you need after that (trap adapter usually).
You'll probably need one of those clamp on rubber caps, or an inflatable
Typically the clean-out tee where the system leaves the building.
I glued test caps in all sink outlets as I was installing our plumbing
system. To minimize roof penetrations, I combined all vent pipes into a
single large vent that exits through the roof. Then I rented an
inflatable test plug (sized to fit my 3" main drain), inserted it into
the house side of the clean-out tee in the back yard, and inflated it
with a bicycle tire pump. To make the job easier, I also got an extension
air hose to reach down to the test plug. Then I drug a garden hose up to
the roof and started filling the entire system with water.
It sounded really scary, with water pouring down through the vent lines
throughout the house, and air bubbling up through the pipes everywhere.
But eventually the system filled up and water started overflowing onto
the roof. I let mine sit for a day or two before the inspector made it
I checked the entire system from the roof down through the crawlspace. I
only found a single tiny leak in a ventline in the crawlspace. It was
VERY slow, maybe a drip every few minutes or so. The inspector never
would have seen it, and it probably wouldn't be a problem in normal use
since the vent line isn't normally filled with water or pressurized. But,
I drained the system, cut it out, and replaced it just for my own piece
After the inspection, I deflated the test plug and had a nice geiser
spout coming up out of the cleanout tee! :) Lots of pressure build up in
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.