[permaculture] Roofing materials and water collection

Neil Bertrando neilbertrando at gmail.com
Thu May 26 19:29:44 EDT 2011

Here's a link to a review article from Australia, which includes the concept
of the rainwater treatment train that occurs throughout the process from
collection to utilization (including drinking).  I think it reinforces many
of the comments above.


<http://www.hydropolis.com.au/Papers/SIA_Coombes1.pdf>We're installing a
painted metal roof this summer from which we plan to harvest drinking water.

Does anyone have advice re: tanks for cold climates (we hit below 0 F (-20
C) for a couple of days each of the past two winters)?   My main concern is
freezing cracking the tank and interrupting our water availability.  We'll
have a groundwater well backup supply, so it won't be devastating, but I'd
prefer not to have to rebuild or re-buy a tank due to their cost.

We're looking for 1000 - 1500 gallon capacity.  Currently I'm looking at
ferrocement or steel culvert style tanks as preferred options.

For site design, I'm considering putting it on a concrete pad or
underground.  I would prefer not to have it underground for access and
maintenance issues.  If on the pad, we're considering putting it inside a
small passive solar storage structure to prevent freezing and utilize the
thermal mass, but this adds significantly to the cost.  another option might
be to plum the downspout directly into the garage where we could insulate
the tank as well (no solar gain though).

any thoughts or experiences with this type of scenario? references, etc?


On Sat, May 14, 2011 at 5:31 PM, Gene Monaco <efmonaco at comcast.net> wrote:

> Does anybody have any long-term experience with Galvalume.
> I have three concerns and no answers:
> 1) Since it is 55% Aluminum-Zinc alloy-coated sheet steel, the aluminum
> might leach into the water giving us Alzheimer's.
> 2) How does it weather over time.  There are a lot of raggy looking metal
> roofs out there.  It might be good for a while, and I know that nothing
> lasts forever, nor should it, but what does it look like after 20 years?
> What happens as it deteriorates?
> 3) Seems like a lot of embodied energy (high carbon footprint).  Aluminum
> from far away...
> -Gene
> Date: Sat, 14 May 2011 07:57:13 +0100
> From: harry byrne wykman <lists at peacetreepermaculture.com.au>
> Subject: Re: [permaculture] Roofing materials and water collection
> To: permaculture at lists.ibiblio.org
> Message-ID: <20110514075713.59a55dbf at humilis>
> Content-Type: text/plain; charset=UTF-8
> 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
> Harry
> http://www.ptpc.com.au
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