Use the drawing’s legend, system labels, connection points and revision history to trace storm and sanitary drainage separately. Compare those records with verified field information and mark unknown routes clearly. A grate’s appearance or a line color alone is not proof of its destination. Arrange professional verification rather than pouring test substances into an unidentified drain.
What should you trace on each drawing?
Use a copy for notes and preserve the original:
| Drawing detail | Question to answer |
|---|---|
| Legend and abbreviations | What does this designer's line or symbol mean? |
| Sheet cross-reference | Does the route continue on another sheet? |
| Structure or cleanout label | Which documented point connects to this line? |
| Direction and elevations | What does the design show about the route and discharge? |
| Connection point | Does it go to a sanitary connection, storm facility or another recorded destination? |
| Revision record | Was this portion changed after the original drawing? |
Trace the route to a documented destination. A label on one inlet does not establish the route of every nearby grate. Floor, trench and area drains help name the visible structures without deciding where their pipes go.
How reliable is the record?
Separate an approved design from a field record. The federal UFGS closeout specification describes recording installed conditions and changes for its contracts; it is a documentation example, not a rule requiring that package for every private property.
Permit plans and as-built records have different purposes and limitations. Mark an unverified route as unknown, even if the design suggests a likely destination. Compare accessible structures safely; do not enter a pit, tank or manhole to confirm a drawing.
What if a route remains unknown?
Have a qualified contractor propose an appropriate verification method and coordinate any required utility or authority permission. Do not pour dyes, cleaning chemicals or wash water into an unidentified drain as a casual test. Parking-lot wash water explains why the destination matters.
Record the verified scope, date and remaining uncertainty, then update the building's working map. Keep it in the closeout file. Use that map during a preconstruction walk so maintenance and tenant changes begin with the same documented information.