Dangerous downspout?

Q: I'm planning to divert my downspout into a rain barrel. Is water from a coal tar roof okay to.

Q: I’m planning to divert my downspout into a rain barrel. Is water from a coal tar roof okay to use on plants and vegetables?


A: Here comes the rain again, and, honey, you’d better have a barrel to catch that free water falling from the sky.

Though more than 2 million lakes dot this country, Canadians should never take access to that blue gold for granted. (Water wars are coming, my friend -? just ask H2O gurus like Vandana Shiva and Maude Barlow). And yet we squander the resource like there’s literally no tomorrow. In fact, our water use doubles come summertime, when we pull out our hoses and sprinklers. Not good for a country that’s already the world’s largest per capita agua hog (after the U.S.).

Luckily, just putting a rain barrel at the base of your downspout can help. A hell of a lot of pitter-patter falls on that roof of yours every year. (Just .5 centimetre of rain drizzling on a 305-square-metre roof creates over 500 litres of runoff.) In a major storm, that runoff helps flood basements as well as sewers, which can, and often do, overflow, seriously polluting nearby creeks and waterways.

A rain barrel, on the other hand, can store hundreds of litres of free water for use on your property any time you need it. Not only will you have lower water bills in July, but your plants will be much happier drinking warm, chlorine-?free water.

Question is, will your roof surface mess with that blissful picture? It all depends on what’s topping your home and what you’re planning on watering. Old painted metal roofs could contain lead. Cedar shingles can be treated with dodgy chemical preservatives and flame retardants. Coal tar and asphalt are made of petrochemicals. All of the above could potentially leach into your rainwater. In all honesty, though, no one’s really done much testing on this front.

From an official government health perspective, unless you’re drinking your rainwater, any roofing material will do. Still, many horticulture experts advise you to take the precautionary approach and stick to splashing that rain-barrel water on your ornamental plants and lawn only. But you’ll find just as many green-thumbers who’ve been quenching their watercress and watermelons with rainwater for decades and are still alive to tell the tale.

If you’re feeling cautious but willing, you could just water your fruit-?bearing veggies like tomatoes/cukes/peppers with the stuff (instead of your root or leafy veggies), since they absorb fewer contaminants like lead.

By the way, you can get yourself a rain barrel from any hardware store these days. (President’s Choice even makes one.) Some are designed to look like planters, others are collapsible, and most are just plastic vessels made in the pattern of old-?fashioned wooden barrels. The city will sell you one for $85. TerraCycle even makes some out of old wine barrels. Look for them soon in select Home Depots.

If you’ve got a bit more space, check out RiverSides’ 500-litre rain barrel. Since it holds double to triple the volume of regular models, it won’t fill up quite as quickly.

Not sexy enough for you? The peeps at Moss Sund Architects figured out how to bring some serious style to the world of rain barrels. Their ivy-?covered Cista holds nearly 370 litres in a slender 2.4-metre-high, 55-centimetre-wide design.

If you’re serious about never turning on the hose and space isn’t a factor, check out rain cisterns. They’re just like rain barrels, only a lot bigger (typically holding 6,000 to nearly 20,000 litres) and can actually be buried underground. With a good greywater system, you can use the water collected here to flush toilets and wash clothing.

Whatever barrel you buy, just be sure to avoid the kind made of PVC/vinyl, and look for one with a mosquito screen and a diverter valve to steer water away from the house when the barrel is full. I’d also look for one with a spout right at the very bottom of the barrel (otherwise you’ll have about 10 centimetres of water pooled on the bottom when you empty it).

And since a rain barrel can weigh over a ton when full, make sure it’s installed on a firm, level surface like patio stones, and elevate it several centimetres or you’ll be fighting gravity all the way to your geraniums.

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