Spring on the way, and spring in us if we choose it

Fellow water imbibers: I’ve been asked this lengthy, well-informed and valuable question:

‘Michael,

I’m planning a new house with two 20,000L rainwater tanks, possibly of stainless steel, and I’m trying to decide what roof and gutter and downpipe materials to use.  I’ve read the reports of Mirela Magyar’s studies on metal contaminants in rain water tanks in Melbourne, and I’m reading your book Sustainable House (2010).

Do you have any opinions on the best roof materials to minimise health problems (and also to minimise embodied / lifecycle energy)?

In one of Magyar’s studies, 5 out of the 7 tanks with zinc levels higher than recommended had a galvanised roof.  I wonder if these tanks had first flush diverters, and if not, could this have minimised/eliminated the problem?  (I understand that inorganic contaminants tend to attach to particles in sludge.)  Is your roof galvanised?  How old is it?  Do you know if older galvanised iron would lose more or less of its zinc into rainwater than new?

I’m also considering zincalume, which I expect would last longer, perform better thermally, and be cheaper, but I imagine that both zinc and aluminium could end up in the water from it.

And I’ve considered colorbond, which should also last longer and, if white, perform better thermally, but I’m concerned that when it starts to deteriorate (I think it’s warrantied for 20 years), contaminants from the flaking surface, and its primer (containing strontium chromate, whose dust is a suspected carcinogen) and the underlying metal (zincalume) could end up in the rainwater,.

I’d be grateful of any thoughts, answers and references to help me decide.’

Let’s cut to the chase.

In 200 years of western culture no one has died drinking rainwater in Australia.

About 3 million Australians drink rainwater every day.  We’ve drunk it here in this household, , we one to four folk, for 15 years and most damage done to us has been from bad whisky, too much ice cream and too much food.

Now, to the details.

I go for Colorobond white or pale every time; it’s accredited under the standard that vets products suitable for harvesting rainwater: AS…..

As wells as giving long term clean, healthy water it reflects light and heat and cools the house or office below.

See, for example:

My roof is over 20 years old.  Rusty, corrugated iron.  Water quality here meets National Health and Medical Research Council 2004 Guidelines: and see,

www.colorbond.com…

The key to my clean water is the first flush which diverts the first dirty water from the roof to the garden before the rainwater goes into the tank.  Design, product and other details are in my book, Sustainable House:

www.newsouthbooks.com…

May the rain be with you and upon you and within you, go you good thing, Mother Earth

M

Excavation for rain tanks in Peace Park

Feeling frisky, I climbed to the top of the kid’s play equipment today, there to obtain a better view of the excavations for the new rain tanks to be buried in the park.

I took the photo above.

There’s some terrific big, hefty sandstone blocks now stored to one side which have been unearthed by the digger.

It’d be terrific if the Council can have them kept on site and reused in the Park when the job’s done.

We’ll see,

M