For years, I have watered all my plants from my rain barrel, but yesterday, while on a tour of rain gardens around the county, I took a warning to heart: Don’t water your food plants from it. Asphalt roofing shingles, the most common kind, contain contaminants.
I was in the company of experts in the areas of water, soil and gardening — judges of the Rain Garden Alliance’s rain garden contest and Beth Dutton, program manager for Three Rivers Wet Weather.
Beth shared with me a letter from a schoolyard habitat specialist with the Maryland Association for Environmental and Outdoor Education. It reads, in part:
“It is the first flush of concentrated pollutants funneling fown from the shingles that is of most concern,” wrote Julie Dieguez. “It is a pretty solid recommendation across the board that you should always wash vegetables and other edibles thoroughly regardless of gardening and watering methods.”
“If appears that the type of roofing you have is the main concern,” she continues.
If you have wood shingles or shakes that have been chemically treated with chromated copper arsenate, definitely do not water your edible plants from the rain barrel. If you have a cooper roof or copper gutters, ditto. Zinc anti-moss strips, same thing.
Asphalt shingles may leach “various complex hydrocarbon compounds,” she writes Contaminants on asphalt roofs may also include zincv, lead, chromium and arsenic.
Then there’s the concern about air pollution.
I love my rain barrel. Between my duplex neighbors and I, we have three. We’re diverting 90 percent of the rain water from our gutters to our rain barrels instead of into the combined sewer pipes. That feels good. Diverting water is the main reason I have a rain barrel.
The second reason is to have rain water for my plants. From now on, it will just be for the flowers.