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Explore our glossary of common terminology found in the plumbing industry. Familiarizing yourself with the unique words used will make your overall understanding a bit easier.

Terms used in the field

Our goal is to keep the industry specific and all on the same page when contractors are talking with municipalities and vice versa. These are terms our organization as put together for you to familiarize yourself with:

Offset Joint – Vertical

An offset joint where the piping is out of alignment vertically (up and down)

Soft Blockage

A blockage that yields to the camera but doesn’t move out. Instead it just reseals when the camera is pulled out of it. Typically, we’re talking about things like grease and fats.


A very common trade abbreviation for “Infiltration and Inflow”

Open Joint

Longitudinal displacement of adjacent pipes creating space between the adjacent pipe sections - i.e. the joint has pulled apart or separated.

Offset Joint – Horizontal

An offset joint where the piping is out of alignment horizontally (side to side)


(NOTE: Pretty self-explanatory. However, when we dealt with this we wanted to make it clear that a lot of roots are a problem while a few small fibers are not. We didn’t want to put an impossible demand on someone trying to clear out roots that every single rootlet had to be removed to consider that the line had been cleared. So the first step was to break roots into two groups that indicate a lot of roots that would interfere with flow and just a few isolated roots which would not interfere with flow. That did create another definition though, because tap roots are typically singular roots but are huge and would interfere with flow. Typically tap roots aren’t found in sanitary sewer lines. They’re more likely to be found in storm lines where part of it is open to ground.)

Pipe & Fittings:

Cast Iron Pipe: CI

Concrete Pipe: CP

Gasketed PVC Sewer & Drain Pipe (Green): SDR 35

High-Density Polyethylene Pipe: HDPE

Orangeburg / Bituminous Fiber Pipe: OR

Plastic Pipe: PVC, ABS

Terra Cotta / Vitrified Clay Pipe: VC

Transite Pipe: TS

Wye fitting: Y

¼ Bend / 90 degree fitting: ¼

1/8th Bend / 45 degree fitting: 1/8


A crack that has developed edges that can be seen (Alternate trade term is “open crack”)

Clear Water

Water not discharged from plumbing fixture drain lines. Clear water includes storm water, rain water, surface water, roof runoff, snow melt and subsurface water.


Cracks or fractures have grown and connected to allow a piece of the pipe to move out of alignment, but has not fallen out yet


Loss of all structural integrity – Just pieces piled on top of each other


Clear water that gets into the sewer lateral through an intentional connection – legal or illegal

Root Mass

A collection of roots large enough to affect flow

Fine Root

small root fibers that have no significant effect on flow


A section of piping where the proper pitch of the pipe is lost so in one area the invert (bottom) is lower than it is further downstream causing water to pool in this lower section.

(NOTE #1: WRC / NASSCO refers to this as “water level” which is efficient as it just reports what the inspector sees and he doesn’t have to make a judgement as to why. Perhaps there is water in the line because downstream there is a blockage or there is a dam of sediment on the bottom of the piping holding some water back. When our trade says there is a belly in the line, they’ve already gone further to see if there is a deposit in the pipe problem. If there is no problem downstream, then they need to come back to where the water is in the piping and then note that footage as where the belly is.)

(NOTE #2: Many of us were surprised once we started talking about bellies in the piping at how wide a range there is in the trade as to what is considered “bad”. Nether Providence’s ordinance seems to suggest that a belly or an obstruction of less than 25% could be okay. We could not come to a consensus within the trade regarding how much of a belly is bad, but we did think it was important to indicate how deep and how long of a belly there is in the line. So our training uses both a clock reference and depth to indicate approximate percentages of volume the standing water occupies. Therefore along with the Belly designation should be a number indicating percentages. So “Belly – 25%” would indicate that 25% of the pipe volume was filled with water at that part.)

Hard Blockage

A blockage that the camera cannot push out of the way and it is unclear exactly what is the cause


Ground water coming into the pipe through a defect in the pipe


When a piece of the pipe has fallen out of the piping

Offset Joint

Two sections of sequential piping have shifted so they are no longer in normal alignment. The problems this can cause vary greatly based on whether the joints are displaced vertically or horizontally, how much they’re displaced and, in the vertical situation, whether the downstream section is higher or lower than the upstream section. Suggest that we use a % to indicate how much of an offset there is. For example 25% would indicate that the pipe is out of alignment by 25% of the ID of the pipe. Finally, in order to indicate in a vertical offset, whether the downstream piping is shifted up or down we could use +/- with the % . So for example we could use the abbreviation OJ for offset joint and write OJ-V +25% to indicate that there is a vertical offset joint and the downstream pipe is 25% of the pipe diameter higher than the upstream pipe. (WRC / NASSCO refers to this as “Joint Displaced”)


Out of expected shape – typically used for orangeburg or perhaps real thin PVC

Possible short-hand codes to use:

Crack: C

Fracture: F

Broken: B

Hole: H

Deformed: D

Collapsed: X

Offset Joint: OJ

Offset Joint – Vertical: OJ-V

Offset Joint – Horizontal: OJ-H

Offset Joint – Vertical with downstream pipe higher than
upstream pipe by ¼ of the ID: OJ-V +25%

Open joint – SJ (? – for separated joint???)

Roots – R

Fine Roots: R-F

Root Mass: R-M

Tap root: R-T

Infiltration: I

Scale: SC

Blockage: BK

Hard Blockage: HBK

Soft Blockage: SBK

Partial Blockage: PBK

Belly: BL

Direction Changes:

Line turns to the left: LL

Line turns to the right: LR

Line makes a vertical change with a fitting: LV

Clock References


No edges are able to be seen just a line in the pipe

House trap

a U-bend pipe fitting on the sewer lateral meant to keep sewer gases from the sewer main from getting into the house.


Anything that stops flow.
(NOTE: In the beginning there was just the one word, Blockage. However, trade members thought there should be a designation for a soft blockage. If there is a “soft blockage” then it seemed we needed a “hard blockage”. What about a “partial blockage”? It’s hard to know how far to take it. If there is a brick in the pipe, we would just call it a brick and not a partial blockage. If there is a gas line crossing the pipe, we call it a cross bore and not a partial blockage. What if there is a bunch of grease that has filled the pipe half way? Is that a soft blockage or is that a partial blockage? The terms hard blockage and partial blockage should be used when it’s unclear what exactly is causing it. With WRC & NASSCO they are teaching mainly how to code issues into a pre-formatted program. The inspector cannot use his/her own words. So, they need catch-all phrases for the unexpected. So with WRC and NASSCO, an alligator, an anvil, a dead opossum, a baseball bat and a toy doll will all go into the same category. We don’t have to do that. The inspector can and should write exactly what he sees. We just want to come up with terms for common things so we are all calling them the same thing. This needs further discussion and consensus.)

Tap Root

A large root that will affect flow

Partial Blockage

A blockage that occupies only part of the piping.


Clear water that gets into the sewer lateral through a pipe or fitting defect, such as a hole in the pipe or an offset joint

Cross Bore

Where the original pipe being inspected has another pipe or utility running through it. Typically the other utility was installed by horizontal directional drilling (HDD), but it could be where the inspected pipe was intentionally broken to lay the other utility. What makes it a cross bore is not how the other utility was installed, but that that the other utility can be seen in the inspecting video.


Deposits on pipe walls. Can use a % after it to indicate how much of the ID of the piping is reduced by it. (The trade often only uses this for cast iron pipe and there are lots of names for deposits on other piping. WRC / NASSCO uses the term “Encrustation”)

Curb trap

In the greater Philadelphia area, house traps were traditionally placed near the curb and so were usually referred to as curb traps. The term curb traps was then still applied to house traps that were located in the ground outside even if they weren’t close to the curb.

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