permaculture

["Jonathan Bentley" <jwb@sanynet.ne.jp>]

Hi Frank
The following is some caveman chemistry regarding zinc. The US RDA for zinc
is 15mg, and many zinc supplements provide about 50mg of zinc oxide, zinc
gluconate, etc. The FDA has set 5 PPM as a max for zinc in municipal
drinking water. Above this level you can actually taste the zinc -- it's a
tart electric taste, like putting your tongue on a weak 9V battery :^o
While unpleasant to the palate, drinking 2 liters of water with 5 PPM of
zinc would only add 10mg to your diet (pH and other variables will affect
how this zinc is received by your body). A side note: Many plants are more
sensitive to zinc than humans are. To summarize, while hazardous levels of
lead and other hazards are tasteless, potentially dangerous levels of
dissolved zinc will be obvious.

Have you checked out the rainwater treatment system (WOM) put together by
SSA (the Earthship folks)?
http://www.earthship.org/systems/water/catch_water.htm
paz y bien,
Jonathan Bentley

~~~~~~~~~~~~~~~~~~~~~
"Life is short, but it's wide."
        Utah Phillips


>The only concern I have about metal roofing is possible leaching of
metals...I
>saw references to two studies that showed way above average zinc etc. PPM's
>even after a few hours. Someone siade newre baked on ceramic? finishes
would
>solve that...is that the same as enameled metal finishes?

>I'm not sure what the best , simple, inexpensive water purification system
is?