North Seattle plumbing / guide 28
One sink, tub, or shower that drains slowly does not prove a building-drain or side-sewer problem. Record ordinary pooling and clearing without pushing the fixture toward overflow.
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A seasonal change may coincide with the symptom, yet the fixture's own use history, stopper position, visible debris, and prior treatment are more direct observations.
Estimate how high water pools, how long it takes to clear, when the problem recurs, and whether one nearby fixture behaves normally.
Stop before the rim, avoid chemical mixing, and tell the provider about every cleaner, plunger, snake, or earlier service attempt.
What to observe now
Keep the notes factual. A visible clue can direct an inspection without proving what is hidden.
Use normal flow and stop well before the basin, tub, or pan fills.
Count the interval from shutoff until the last standing water leaves.
Note ordinary open and closed behavior without taking the assembly apart.
Check one safe adjacent drain only when added water cannot spread the problem.
Include treatments and service dates so the inspection starts with the full history.
Responsibility
Closeout record
Keep the inspected access point, removed material description, cleaned or replaced part, safe flow demonstration, product caution, and instructions for recurrence.
Current primary sources
Public procedures and status can change. Use the source that owns the decision.