The answer to 'why is my soffit water stains' is that water stains on the soffit are typically caused by a roof leak or improper ventilation. The soffit is the underside of the roof overhang, so any water leaking from the roof or condensation buildup can lead to visible stains and discoloration on the soffit.
Some common causes include worn or damaged roof shingles, clogged gutters, poor attic ventilation, and improper installation of the soffit. The stains may start small but can worsen over time if the underlying issue is not addressed. It's important to identify and fix the root cause to prevent further damage.