Mark Borgerson wrote:

snip
You still haven't shown why you think the bacterial fragments
are 'toxins'. Toxins are generally considered to be special-purpose
chemicals released by an organism for a specific purpose.

Toxin:
"A poisonous substance, especially a protein, that is produced by living
cells or organisms and is capable of causing disease when introduced
into the body tissues but is often also capable of inducing neutralizing
antibodies or antitoxins"

You're talking about "exotoxins". Larry is talking about endotoxins
(I'm assuming).


This definition doesn't seem to include fragments of dead bacteria.

Endotoxins are typically lipopolysaccharide components of the cell
membranes of gram negative bacteria (like pseudomonads which like to
live in water). When the cells are lysed, the endotoxins are released.
However, and a big however it is, endotoxins are generally in the
range of 10 kda to 100000 kda or more, and the RO membranes are more in
the 1 kda range relative to retention.

We're talking *drinking* water here. The FDA allows the manufacture of
Water for Injection to be manufactured with dual pass RO (i.e. safe for
injecting into your veins). Problems do arise, however, when the
pressure is jacked up to deal with poorly maintained plugged membranes,
and you get seam or joint cracks, o-ring leaks, etc. that allow water to
bypass the membranes.

Like any other critical system, RO needs to be maintained properly to
work properly.

Keith Hughes