We have had water collected from a composition roof at this location tested by an EPA certified laboratory. The water passed (actually far surpassed) all epa, and local requirements for potable water purity after being run through a small slow sand water filter (filter 1). Composition roofing material can be used for rainwater collection. An excellent study was done regarding this issue by the Texas Water Development Board (P.O. Box 13231, Capitol Station Austin, Texas 78711-3231), that further confirms our results. “Effect of Roof Material on Water Quality for Rainwater Harvesting Systems”
Carolina B. Mendez
Brigit R. Afshar
Kerry Kinney, Ph.D.
Michael E. Barrett, Ph.D.
Mary Jo Kirisits, Ph.D.
A new (composition) roof has been installed on the water collection surface that feeds 3 of the slow sand filters in operation here (filter 1, filter 5, and the (very small) diy experimental filter mentioned in the extensive post before this one. According to the best information we have, this roofing material does not have moss killer (zinc) embedded in it. As time passes, we will do tests on the water for copper, and zinc compounds – as these are the most common chemicals used to kill algae, and moss. The MSDS reports that the roofing material contains :
Granules – 20 – 45 NE NE NE
Limestone 1317-65-3 25 – 45 5 mg/m3 – resp.15 mg/m3 – total3 mg/m3 – resp.10 mg/m3 – totalREL: 5 mg/m3 –resp.10 mg/m3 – total
Oxidized Asphalt 64742-93-4 10 – 30 NE 0.5 mg/m3(inhalable fraction, as benzene-soluble aerosol)5 mg/m3 – ceiling (15 min. fumes)
Crystalline Silica 14808-60-7 0 – 10 10 mg/m3 / (% SiO2 + 2) – resp.0.025 mg/m3 REL: 0.05 mg/m3 –resp.
Fiberglass Mat 65997-17-3 1 – 3 1 f/cc – resp. 1 f/cc – resp. REL: 5 mg/m3 – total fibers
Titanium Dioxide 13463-67-7 0 – 4 15 mg/m3 – total 10 mg/m3 – total REL: lowest feasible concentration
It is a “50 year” roof. So far, the water has been quite “clear”, (non-turbid) and not discolored. The shingles are: Timberline® Ultra HD™ Lifetime Shingles