[permaculture] rainwater and potability in large cities

Douglas Barnes duckrace2000 at yahoo.ca
Wed Jun 4 15:39:07 EDT 2008


I've have the same concern about this myself. I used to live in Tokyo and dioxin fallout was and is a concern there. I asked Bill Mollison about rainwater harvesting in this sort of environment and he said that the only thing you can do in areas of dioxin contamination is move. Ultimately, I did just that.

As far as dioxins go, if they are a pollutant in your area, you can't do much to avoid them. They will be in local produce and in local water. There will be other particulate matter too - fallout from diesel engines, from industry, etc. I had hoped that I could get some of Tokyo's rainwater tested via a contact at the agricultural university in Tokyo, but it never materialised.

For Tokyo, one would be making a comparison for which rainwater collection system would be cleaner: rooftop or city reservoir. I've walked around the Saiyama reservoir in Tokorozawa (though I wasn't supposed to) and being a dam, it just harvests rainfall. I'll formulate the question of which is safer by including what I saw in and around the reservoir: Is it safer to harvest water off of a steel or clay roof, or is it safer to let it filter though the ground and all the appliances, batteries and old cars that the residents living around the reservoir illegally dumped? 

 Douglas JE Barnes 
EcoEdge Design 
dbarnes at ecoedge.ca

----- Original Message ----

Message: 4
Date: Tue, 03 Jun 2008 19:56:54 -0300
From: Guilherme Neves Castagna <guilherme at permacultura.org.br>
Subject: [permaculture] rainwater and potability in large cities
To: permaculture at lists.ibiblio.org
Message-ID: <4845CC36.5010801 at permacultura.org.br>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Saludos ermanos,

    Jody T put up a question on whether rainwater could be safely used 
for drinking, and more. Question that comes up to my mind is, suppose 
I'm in Tokyo, New York, Mexico City, or Sao Paulo (cities with over 
10million ppl), what will the rainwater drops collect along the way that 
will turn it inadequate to human consumption (other than the drop in 
pH)? Heavy metals, sulphur dioxide, what else? Has anyone tested 
rainwater for potability in similar situations? Can I eventually turn it 
potable through the use of reed beds, sand filters, and the like? Some 
friends of mine live in Sao Paulo (Brazil) and are devising alternatives 
to the impending failure on the public water distribution systems, and 
rainwater is their only option.

    I sincerely appreciate your comments on this topic...


Gui Castagna - Design Ecol?gico
fone/fax: +55 (12) 3832-1476
celular:  +55 (12) 9702-9203

Web: www.livrariatapioca.net +
Skype: guilherme.castagna


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