What to notice
Check the ordinary-use history
Note floor drains, guest fixtures, laundry standpipes, or condensate connections that have not been used recently. A provider may ask whether the trap receives water by design. Do not pour chemicals, cap an opening, or alter a vent to test an odor. Record whether ordinary approved fixture use changes it.
Separate fixture seals from drainage patterns
A toilet seal, trap, cleanout, vent, connection, wastewater backup, or non-plumbing source may produce an odor in the same area. Look for visible leakage or gurgling without dismantling anything. Several affected rooms or odor tied to drainage gives different context from one seldom-used drain.
Request the basis for an invasive step
Before smoke testing, opening walls, removing a toilet, or altering piping, ask what observations support it and how the property will be protected. Confirm what the test can and cannot establish. Ask who restores removed fixtures or finishes and how the result will be documented.