[permaculture] Roofing materials and water collection

harry byrne wykman lists at peacetreepermaculture.com.au
Sat May 14 02:57:13 EDT 2011

Here's a quote from a write-up of a recent study:

Cockrell School faculty and students conducted an in-depth study --
recently published in the academic journal Water Research -examining
the effects of conventional and alternative roofing materials on the
quality of harvested rainwater. The study, led by civil, architectural
and environmental engineering Assistant Professor Mary Jo Kirisits,
showed that, of the five roofing materials tested, metal (specifically
Galvalume®), concrete tile and cool roofs produce the highest
harvested rainwater quality for indoor domestic use. The study also
showed that rainwater from asphalt fiberglass shingle roofs and
increasingly popular "green" roofs contain high levels of dissolved
organic carbon (DOC). Although other potential pollutants can be
significantly lower on green roofs (turbidity and aluminum), the high
DOCs are significant where these roofs would be used for potable
rainwater collection.

Source: Rainwater harvest study finds roofing material affects water
quality : www.sciencedaily.com


On Sat, 14 May 2011 14:29:52 +1000
Robyn Francis <robyn at permaculture.com.au> wrote:

> I don't have a link to the report, but in the mid '90's our local
> Southern Cross University did a major study of roof water quality
> getting 100's of local residents to send in samples from their
> rainwater tanks stating the roof material and kind of water tank.
> They found the best quality rainwater was harvested off colourbond
> metal roofing (the paint is baked onto the metal so doesn't peal or
> flake) and stored in cement water tanks. Robyn
> On 14/05/11 9:49 AM, "Stephen Sherman" <spsherm at msn.com> wrote:
> > We have a small building which is going to be roofed, and I am in
> > the middle of choosing a roofing material. I would like to keep the
> > option of collecting roof runoff open, and keep the roof as
> > fireproof as possible. Those are the primary concerns for this
> > choice of roof.
> > 
> > I have heard/read the negatives about using water which came off
> > asphalt shingle roofs, so those are probably not an option. That
> > would seem to leave only a few choices:
> > 
> > Ceramic tile roofs are out, due to their weight and structural
> > concerns.
> > 
> > Galvanized metal roofing seems like the best choice perhaps, for
> > easy of use, fireproof-ness, and runoff quality (as far as I have
> > heard).
> > 
> > Another potential option is painted metal roofing (usually
> > available in wider sheets than the plain galvanized, and longer
> > lasting. Only problem is no manufacture seems to have any data
> > about runoff water quality from their painted roof materials.
> > 
> > I was wondering what people thought about these options; If there
> > are any others which I've missed;  and if anyone had any hard data
> > on painted metal roofing leaching whatever into the water runoff.
> > 
> > 
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