Roof runoff can carry environmental contamination regardless of the roofing material. Malarkey does not recommend using roof runoff to water gardens
Malarkey technical bulletin: Use of Roof Water Runoff.
What this means for your roof
Roof runoff can carry environmental contamination regardless of the roofing material. Malarkey does not recommend using roof runoff to water gardens. Its bulletin discusses contamination and studies rather than certifying collected water as safe to drink. A roof-water system requires its own treatment and use assessment.
A useful question for your contractor
Ask a qualified rainwater-system professional about the intended use and water-quality requirements before connecting a collection system.
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: July 2026. The date shown identifies the manufacturer document used for this summary.
Read Malarkey: Use of Roof Water Runoff
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.