Customer tested that there is a stain on floor behind bathroom. Found slight discoloration on hard wood flooring behind bathroom. No plumbing above this tested everything in the bathroom to find no issues. Vanity has separated from the wall. I believe the leak could be coming from water getting behind vanity. Customer stated that the discoloration has been there for a long time. I informed him that if it was a water leak or drain leak the floors would have bowed outwards. No plumbing issue detected. Job is completed