Mk Neal wrote:I use rainwater from asphalt-shingle roof for watering my garden. I do not notice shingle detritus in mine though; are your shingles very new or very old, maybe? Also, my water barrels have screen at top intake and the outlet/tap is about 1.5 inches above the bottom of the barrel.
Kenneth Elwell wrote:Your comment about the accumulation of roof debris in the tank makes me think that water is steeped with that stuff, as it sits waiting to be used. I'd try to keep it out of the tank in the first place.
There are "first flush diverters" that dispose of the first amount of water to hit the roof in a rain. Presumably the roof debris, leaves, bird poop, and bugs get washed off the roof and dumped, and after that, the cleaner water goes to your tank.
Or you could put some sort of filter, like a radial flow filter or a slow sand filter to capture the debris and leave you with "cleaner" water. It will still have leachate from the asphalt, but not so many particles soaking in the water all year.
Do you use well water for toilet flushing? maybe this is another use for the roof water? Not sure if code technically would allow for you to plumb rainwater to the toilet (to protect your drinking water), but a flush with a pail (especially easy for #1) gets around that issue.
Douglas Alpenstock wrote:We use water off asphalt shingled roofs for irrigation. Our well water has too much dissolved solids (salts etc.) to keep tomatoes and squash and strawberries happy.
I've never had a sense of a problem. For example, I would expect to see a hydrocarbon sheen on the top of the water barrels -- and never have. When we had some new shingling done, though, we let the initial water after some good summer heat and rainstorms drain into non-food and shelterbelt trees. It seemed a sensible precaution.
C. Letellier wrote:Suggest try testing the water. Older roofs should be losing very little dangerous. Most of the volatiles should have washed away or evaporated over time. So risk should be small.