We decided to put together a brief guide to PACP codes. Now, if you’re like most people reading this, you probably already know what those are. However, we’re including a bit of background for those who aren’t familiar with them. So, if you’re a NASSCO member and using PACP codes on a daily basis you can just skip over this next part and head straight to the codes.

What is the Pipeline Assessment Certification Program (PACP)?

Over a million and a half miles¹ of drainage pipe lie deep underneath our city streets. According to Reese Tisdale, president of Bluefield Research, some of the pipes are so old they date back to the mid 19th century¹. Some of them are even made of wood². Of course, like everything else, drainage pipes don’t last forever. However, with proper maintenance, they can last a long time. That’s why inspections, and a standardized protocol for recording what we find during inspections, are important.

The acronym PACP stands for the Pipeline Assessment Certification Program. This program was created in 2002 by the National Association of Sewer Service Companies (NASSCO), a professional organization that sets industry standards for underground infrastructure. The Pipeline Assessment Certification Program provides municipalities and contractors with a standard method for coding defects and other information found during CCTV sewer pipeline inspections.

PACP has been adapted for use by other types of pipe systems including storm, water, dam, and levee. NASSCO also has a Manhole Assessment Certification Program (MACP) and a Lateral Assessment Certification Program (LACP). PACP is a prerequisite for both.

Why is standardization important?

Before the Pipeline Assessment Certification Program, there was no standardized protocol for managing pipeline inspection data. Some owners created their own system while others allowed the technicians to collect data without using a standard. That was a problem because without a universally-adopted standardized system for recording what you’re observing it’s difficult to compare the condition of one pipe with another in any meaningful way. PACP standards make it much easier to compare the condition of segments within a pipe network. The result is greater insight into how our underground infrastructure deteriorates.

PACP: Four categories of defects

The Pipeline Assessment Certification Program identifies defects and separates them into four categories of codes: structural, operational & maintenance, construction, and miscellaneous. Each defect code is graded from 1 to 5, with 5 indicating the most serious defect.

Because there are so many codes to remember, PACP is not an easy system to learn. New users need to constantly compare what they see during inspections to the descriptions and photos in the PACP catalog.

Let’s take a brief look at each of the four categories of defects. Here’s a color-coded chart³ that highlights these four categories so you can follow along.

NASSCO PACP structural defect coding chart

Structural defects

The structural defect groups(and the letters that represent them) are…

  • Cracks (C) : These are lines that are visible on the surface of the pipe.
  • Fractures (F) : Fractures are cracks that have visibly opened and created a gap.
  • Broken (B) : These are pieces of broken pipe that aren’t in their original position.
  • Hole (H) : Holes indicate that a piece of pipe is missing and either soil or a void is visible.
  • Deformed (D) : A deformed pipe is one where up to 40% of the cross-sectional area is distorted.
  • Collapse (X) : When more than 40% of the cross-sectional area is distorted, the pipe is in a state of collapse.
  • Joint (J) : This code is used to indicate displacements at pipe joints.
  • Surface damage (S) : The surface damage codes begin with roughness and increase all the way to a code indicating a missing pipe wall. There are also codes indicating surface spalling and one for a chemical attack.
  • Buckling (K) : Buckling refers to deformations in pipes made from flexible material like corrugated metal, PVC, PE, and plastic.
  • Lining failure (LF) : This code is used for describing problems with relined sewers such as discolorations and blistered linings.
  • Weld failure (WF) : This refers to weld failures in metallic, butt-fused, and spirally wound weld pipes.
  • Point repair (RP) : The code is used when part of a pipeline or sewer has been relined or repaired.
  • Brickwork : This is used when areas of a sewer have missing or displaced bricks, missing mortar, or where the invert has dropped. (There isn’t a code letter for Brickwork.)

NASSCO PACP operation and maintenance coding chart

Operation and maintenance

The operation and maintenance defect groups(and the letters that represent them) are…

  • Deposits (D) : Deposits, such as grease and gravel, in pipes cause a number of problems including flow turbulence and blockages.
  • Roots (R) : Describes the various types of roots found inside sewers. Roots get into pipes through defects. (An entry is made for the roots and another entry for the structural defect.) Roots are classified as fine, tap, medium, and ball.
  • Infiltration (I) : This is when groundwater seeps into the pipe via defects or porous areas in the pipe wall. An entry is made for the infiltration and another for the structural defect that caused it.
  • Obstacles/Obstructions (OB) : This is for medium and large-sized obstacles or obstructions in the pipe. (Use the Deposits code (D) for small objects in the pipe.)
  • Vermin (V) : This code is used when you actually see vermin in the pipe.
  • Grout Test & Seal (G) : Used to record the results of grout sealing work.

NASSCO PACP construction features coding chart


The construction defect groups(and the letters that represent them) are…

  • Tap (T) : Tap is used to record various conditions associated with the connection point between a building’s main sewer line and the municipal water system.
  • Intruding Sealing Material (IS) : Used for recording where the material used to seal the joint is intruding into the pipe (hanging, broken, or loose).
  • Line (L) : This code is for obvious bends or changes in the sewer line. It’s usually associated with brick sewers.
  • Access Point (A) : An access point refers to either the CCTV survey’s entry or exit point. These are often manholes.

NASSCO PACP misc coding chart

Miscellaneous features (M)

The miscellaneous code (M) is used for anything that isn’t covered in the other PACP defect codes.

The 1-5 Condition Grading System

As we mentioned earlier, each PACP code has a pre-assigned condition rating associated with it. (In other words, it is not assigned by the technician.) The defect codes are graded from 1 (minor) to 5 (significant defect).

Where to go for more information about PACP codes

NASSCO (National Association of Sewer Service Companies), the organization that created the Pipeline Assessment Certification Program, should be your ‘goto’ source for information about PACP codes. Their website contains information on training, certification, and even a job board.



  1. $300 Billion War Beneath the Street: Fighting to Replace America’s Water Pipes, https://www.nytimes.com/2017/11/10/climate/water-pipes-plastic-lead.html
  2. Aging of Water Mains Is Becoming Hard to Ignore, https://www.nytimes.com/2009/04/18/us/18water.html
  3. https://www.nassco.org/sites/default/files/pacpcodechart_0.pdf