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permaculture - Re: [permaculture] Roofing materials and water collection

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  • From: "Lawrence F. London, Jr." <venaurafarm@bellsouth.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] Roofing materials and water collection
  • Date: Sat, 14 May 2011 00:31:42 -0400

On 5/13/2011 11:39 PM, Stephen Sherman wrote:
Thanks, appreciate the experience. Reinforces what I had heard elsewhere
about the longevity of the painted roofing.

Question still remains (in my mind at least) is it safe to drink the
water which comes off this painted roofing? Would you do it on a
regular basis?

There's the difference. I do not know what chemicals may diffuse from painted roofing into rainwater which may have a low pH. With a galvanized metal roof you are dealing with the galvanizing chemicals which may include zinc which is toxic and may diffuse into acid rainwater. As for fasteners it would be important not to use leadhead nails to attach the roofing; this goes without saying. Maybe the painted roofing would be safer. What about bird doo and rotted vegetation, dust particles of all sorts that get mixed with rainwater?
Purchase one panel each of the 5V galvanized and one of the painted - mount them outside and collect water that runs off them - then have it tested. Also, get MSDS's (Material Safety Data Sheet) for each product and read what chemicals are in the paint and what the galvanizing agents are then do extensive Google searches for more info on potential toxicity from these roofing materials that might affect collected rainwater used for human consumption - maybe OK for washing but not food prep or drinking - maybe some filtering required.
question put to Google like:
"toxicity problems with rainwater collected off metal roofing"

Tried that phrase and got:

Information on Zinc Oxide in Construction - Zinc Metal Roofing Systems
The run-off water can contain zinc ions. Since zinc is an element essential for life and most organisms ... For instance, rainwater collected from VM ZINC roofs, can be used without any known problems for watering plants. ... Actually there are many types of heavy metals some that are toxic and some that are not. ...
www.metal-roofing-zinc.com/zinc_roofing_basics.htm - Cached - Similar

and:

http://www.homesteadingtoday.com/archive/index.php/t-376478.html

Key reply:
"I wouldn't drink rainwater off a roof unless it had been sterilized by some means, boiling or chlorine or such. Bird poop can carry some nasty parasites and pathogens. You can do it, and get away with it, but it is a gamble."




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