PACP codes roots as fine, medium or ball, which shows progressive blockage. A root ball is graded 5, and fine roots 2, in one published example. Seattle's utility says minor intrusion usually doesn't affect the pipe, while roots blocking half the pipe or more will affect it and call for cleaning and frequent re-inspection.
What fine, medium and ball mean
In the PACP coding system, roots sit in the operation and maintenance family, not the structural family, because they affect flow rather than the pipe wall itself. The codes run from Fine (F) through Medium (M) to Ball (B). Geocadra describes the range as "indicating progressive blockage." Its example of how the grades scale: a root ball is Grade 5, more severe than fine roots at Grade 2.
Some reports use simpler wording instead, such as minor, moderate and severe. Seattle Public Utilities rates root damage this way.
What a utility says to do about each level
| Rating | What Seattle says | Recommendation |
|---|---|---|
| Minor | Typically no effect on the working function of the pipe. | Inspect three to five years after the original inspection. |
| Moderate | May or may not affect the working function. Root intrusions will likely increase in severity over time. | Inspect three to five years after the original inspection. |
| Severe | Obstructing 50 percent or more of the pipe can or will affect the working condition. | Inspect every one to two years. Perform routine cleaning. |
Seattle adds that roots are attracted to water and nutrients in the sewer, that older concrete and clay pipes not built with watertight joints are especially at risk, and that roots can crack pipes and cause sewer backups. Those are one utility's intervals for side sewers. A commercial line with heavy use or a history of backups may warrant a shorter cycle.
Roots are a maintenance item and sometimes a symptom
Roots that show up at a joint may be entering through a gap, so read the report for an offset joint or a crack at the same footage. Cutting the roots restores flow, but the opening is still there. See how to keep roots from coming back, and signs of tree roots in a sewer line.
Removing the tree isn't a reliable fix either. Seattle notes that a tree's roots grow up to two times the length of the tree's height, so removing trees above or near a side sewer will not likely fix a root problem.
What to ask about your report
- The rating and footage of every root entry.
- Whether roots were cut during the inspection or only observed.
- A re-inspection date that matches the rating.
For how the code system works, see what PACP coding is. HQ can clear the line, camera it afterward and give you free estimates with upfront pricing on any repair.