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Keith Hughes

wrote:
On Sep 15, 2:48 pm, Larry wrote:
... I didn't attack RO, by the way. I only pointed out what I had read of
the bacteria trapped on the high pressure side of the membrane breaking
down, then releasing their toxic load into the feedwater, which WAS small
enough to pass through the membrame into the drinking water on the other
side. It's a serious problem for many drinkers if it's not corrected. ...

Is it a genuine "serious problem" or a theoretically possibly "serious
problem"? How many is "many"? I've never heard of a single case of a
cruiser getting sick or even suspecting that they got sick from their
RO water. It seems to me you've gotten pretty worked-up without any
disinterested evidence at all. It would be nice to know if there is
any evidence from anyone not selling a competing product that the
problem exists and if if does exist is would be nice to know how
dangerous it is. Are we talking about the mild flue like stuff that
we all get from our food and water as a part of living in a complex
world or need we be worried about something more deadly?

It's *only* a serious problem if you don't maintain your RO. Membranes
*will* develop a biofilm, and it is possible that, with serious neglect,
you get bacterial growth-through (i.e. bug colonizing the membrane and
shedding on the downstream side), but extremely unlikely. Much more
likely is the increased pressure caused by fouling with biofilm causes
membrane compaction, severely restricting flow.

With RO, you need to monitor the pressure, and the flux rate (flow
through the membrane) and take some corrective action when you start
seeing a downward trend. And RO membranes have to be replaced - they
don't last forever.

Each technology has its tradeoffs. The bioburden of RO water from a well
designed and maintained RO system will be extremely low - far lower than
tap water. The vegetative bioburden from a stove-top type still will
generally be lower, but there are plenty of bacillus and mold spores
that will cruise right through it without a problem.

Let's face it, if it *were* that big of a problem, you'd die if you went
swimming in your pool, or the ocean, or drank water from a fountain, or
in a restaurant, or....

Just be a little smart about where you draw water from, and don't let it
sit around in a dirty vented tank, and maintain your equipment (still or
RO) and you won't have a problem. Routinely maintain your tanks, and
that water won't be an issue either

Keith Hughes