[Cob] roofing

[Amanda Peck]

True, and at least one of the rainwater collection links (Australian or an 
American subsidiary possibly of the same company) mentions that it is not 
certified potable water safe, but what with tradition, AND the fact that one 
manufacturer has bothered to get approval it's almost certainly OK.

I once emailed a standard metal roofing manufacturer about this--got back a 
reply that went on the order of---"No! no no nonono!  There's no problem 
with the base material.  Nothing we add is a problem (at least after it's 
cured).  BUT BUT BUT we have NO control over  any kind of coatings, solvents 
etc. that the people we buy our products from use.  Sounded like potential 
lawsuit avoidance weasel-wording to me--they don't clean the base material 
before they bake on the enamel?  But he was probably right about his 
manufacturing process.

Some of the things that ARE potable water certified sound a lot less 
green--brush-on EPDM (listed in the manufacturer's websites, not here), for 
instance.

The US link:

http://www.leafbeater.com.au/usa/10steps.asp

"Ensure that the catchment surface is approved for potable water collection:
The following are the most popular roofing materials in the order of 
preference: Colorbond Steel Sheet, Zincalume Steel Sheet, Glazed Tiles, well 
fired, Concrete/cement tiles, Clay Tiles & Composite Tiles. Some of the tile 
types mentioned are occasionally made specifically for potable water 
collection. If in doubt, talk to the manufacturer, not the installer of the 
roof, and ask for a certificate of classification for the roofing material. 
All pipes and fittings used within the system must also be approved for 
potable water collection."

The Australian--there are some approved brand names on the site as well:

http://www.rainharvesting.com.au/roof_surface.asp

"Zincalume® has a coating consisting mainly of zinc and aluminium hence its 
name, but it does not come in a grade approved for potable water. That does 
not necessarily mean that it is unsafe to collect potable/drinking water 
from the roof. What it does say though is that it is not "category" 
approved."


...............................
Thad replied to Lance (snipped into nothingness):

   I would not assume that just because water has been collected for 
hundreds of years that there is no leaching or that there are no problems.