permaculture

["John Schinnerer" <john@eco-living.net>]

Aloha,

Check out the Texas Guide to Rainwater Harvesting (PDF document):

www.twdb.state.tx.us/publications/reports/RainHarv.pdf

Some additional docs at the Austin, TX RWH page:

http://www.ci.austin.tx.us/watercon/rainwaterharvesting.htm

I have skimmed some of the docs from the conference previously posted in
response to your question - most seem to raise more questions than they give
answers, but there look to be some valuable contacts available there.

> Also I have heard that after one hour raining  the remaining collected water
> can be consiered safe to drink.
> Is that true?

Rain does bring particulates suspended in the air to the ground over time.  I
assume how long it takes to wash "most" particulates out of the air would
depend on type and intensity of rain and density and type of particulates. 
Whether an hour is "enough" for a worst-case scenario I don't know.

> What strategies/devices can be used in order to separate this "first hour" 
> of
> rainfall from the supposedly good one?

The Texas guide shows the simplest first-flush separator I've seen - no moving
parts, low maintenance.

It's not designed to divert an hour's worth of rain as they show it (unless
it's very light mist ;-), but the design could easily be modified to do so, or
the diversion could be manually switched at any desired time.

Consider the possibilities of living roofs to filter possibly polluted
rainfall before it even gets to the gutter, let alone the tank, while also
providing their various other benefits simultaneously - "stacking functions,"
etc.




John Schinnerer - MA, Whole Systems Design
------------------------------------------
- Eco-Living -
Cultural & Ecological Designing
People - Place - Learning - Integration
john@eco-living.net
http://eco-living.net