GAF limits its reclaimed-water guidance to ornamental irrigation. Roof runoff should not be assumed suitable for drinking, bathing or watering edible plants.
GAF technical bulletin: Reclaimed water from an asphalt shingle.
What this means for your roof
GAF limits its reclaimed-water guidance to ornamental irrigation. Roof runoff should not be assumed suitable for drinking, bathing or watering edible plants.
A useful question for your contractor
Ask a water-system professional to assess the proposed use, collection materials and treatment requirements.
Ask for the answer to be tied to the actual roof condition and the exact product being installed. Keep the agreed repair or installation detail with your estimate and project photos.
Bulletin edition: 2021 edition. The PDF prints an incomplete date code; an exact release day is not stated.
Read GAF: Reclaimed water from an asphalt shingle
This homeowner summary explains the cited bulletin. The complete manufacturer document and current product instructions govern the installation details. A requirement for one manufacturer or product should not be transferred to another without checking.