Mike
I like the idea of the diverter valve, but if the water goes into the main
freshwater tank is'nt there a chance of contamination from bugs etc. I
am thinking of a catch tank then filtering into the main tank?
Tony

Mike Cobbe wrote:

I have been told that it is quite possible to catch all the water
required for two people when cruising the Caribbean and further south.


Unlikely. It doesn't rain much for long periods and the occasional short
squalls in the fine weather periods don't do much more than rinse the
deck.


Has anyone devised a good system?


We have a deck drain, with a divert valve. The rain either goes to sea or
to our water tanks. Certainly rinse the deck first, but there is no need
to filter the water before drinking.

Our way of looking at it is rain is a useful occasional supplement but we
also have a watermaker.

Mike

is'nt there a chance of contamination from bugs etc

Well, I notice RichH is recommending filtering but we don't think it worth
the effort, provided you clean the deck properly.

Having said that, tanks/pipes can get mould (or whatever) in them over
time. Not really sure why, Peggy can probably tell us. Therefore roughly
every six months to a year, when there is free unmetered water available,
we empty the tanks, give them the bleach treatment Peggy has talked about
and refill them.

Mike

I work in biologically controlled water system. Peggy sells toilets.

Typical atmospheric air will contain 30,000 particles per sq. ft. with a
small percentage of Stochybotris Autra and various Aspergillis spores.
These are removed by filtration. There is NO place on earth where these
spores are not present. Most folks are tolerant of these species, some
are extremely reactive - hence cumulative dosage can be fatal for some.
Play the odds and risk the 'trots' or worse - your choice.
An independent 'collection' tank, then filtration into a (sanitized)
storage tank is the prime recommendation.

One must remember that until the western world corrected and
biologically controlled its water systems and methods .... the leading
cause of death and illness ...and probably the reason for low
life-expectancy was waterborne diseases before that change. The reason
for the low life expectancy in the 'third world' is STILL uncontrolled
water systems/sources. Simply draining rainwater into your boat's tank
is risky and quite archaic in light of modern practices .... and can be
quite dangerous. Even the 'ancients' who filled cisterns from rain
run-off used sand bed filters to purify and create a barrier from
biologically aggressive species while having absolutely NO idea about
such microorganisms. How soon we forget!


Peggy's 'bleach treatment' is a one-size-fits-all case and doesnt apply
to most stagnant (boat) water situations; plus, free chlorine in potable
water is a small risk carcinogen - take your choice.

Peggy's 'bleach treatment' is a one-size-fits-all case and doesnt apply
to most stagnant (boat) water situations;

Why do you say that?

Mike

RichH wrote:

I work in biologically controlled water system. Peggy sells toilets.

Typical atmospheric air will contain 30,000 particles per sq. ft. with a
small percentage of Stochybotris Autra and various Aspergillis spores.
These are removed by filtration. There is NO place on earth where these
spores are not present. Most folks are tolerant of these species, some
are extremely reactive - hence cumulative dosage can be fatal for some.
Play the odds and risk the 'trots' or worse - your choice.
An independent 'collection' tank, then filtration into a (sanitized)
storage tank is the prime recommendation.


What would you recommend? I assume a pre filter and then a fine filter.
In your earlier post you gave the figures as "2-3 micrometers
absalute".When I see filters in our local hardware store they say what
they will do,i.e, protect from cysts, but not the actual size. Are
filter elements standard sizes?
Tony

What would you recommend? I assume a pre filter and then a fine filter.
In your earlier post you gave the figures as "2-3 micrometers
absalute".When I see filters in our local hardware store they say what
they will do,i.e, protect from cysts, but not the actual size. Are
filter elements standard sizes?
Tony


The hardware store filters are not accurate in their retention size. In
fact what they represent is "nominal" rating, which in filter-speak
jargon can mean anything from 50% to approx. 98% removal efficiency (by
weight) at the 'rated' retention size. The rating can be ANYTHING the
manufacurer wants it to be! .... and doesnt (usually) mean that such and
such 'micron rated' filter will retain all such and such particles!!!!
Hardware store type filters are not meant to be used as a 'single pass
filter'; but, are meant to be used wherin the fluid is re-circulated
several times throgh the filter to attain an 'approximation' of the
rating - such as in a (recirculation) swimming pool filtration set.

With cysts, etc. the (very loose) NSF regulations require approx. 98%
removal (by weight) at 1,0 micrometers per single pass of the fluid.
Without an accompanying validation statement on the filter package I'd
be quite dubious of its *true* retention rating ... yes, they will
remove cycts, but probably not to the level required by the NSF regs.
Sadly, most of the 'hardware store' types of filters are rated in the
same manner that manufacturers promote snake-oil. You usually get what
you pay for... a hardware store filter typically in the $2-$6 range, the
same (but precise and compliant) filter from a technical manufacturer
will be in the range of $15-25.

Forgive my snippage;

Tony wrote (snip)
What would you recommend?

RichH wrote (snip)

Hardware store type filters are not meant to be used as a 'single pass
filter'; but, are meant to be used wherin the fluid is re-circulated
several times

in a recent diesel polishing type thread it was suggested to use a
larger micron rated element and to recirculate as much as possible:
not really that much difference between setting up a diesel polishing
system and setting up a water polishing system, 12v water pump and
"standard?" filter housing (find a variety of off the shelf filter
elements at most any hardware store)
already in place on my boat so it would seem all that would be needed
for me to create water recirculation is a TEE with a couple onn/off
valves to divert water back to tank.


You usually get what
you pay for... a hardware store filter typically in the $2-$6 range, the
same (but precise and compliant) filter from a technical manufacturer
will be in the range of $15-25.

? get inexpensive ( cheap !) filters and change often --thats been
my strategy thus far ( string wound filters ), waters OK; but the
waters only passed through filter once on way to faucet..
probably wouldn't cost much ($10-$20 ??) to divert back to tank.....

how important is activated charcoal (AC) in a filter if main tank is
filled from municiple water supply : does AC (or other _______ (?)/
finer micron ratings) rank higher in importance when improvising water
supply ?

My Irwin 37cc is the perfect boat for catching rain off the deck, the
previous owner bought but never installed the valves, figuring the
water we catch on deck will not be of the quality delivered from our
municiple supply and when cruising captured rain will be our greatest
supplement; aside from treating tank/captured water with bleach; if I
added a circulation path to the water system what guidelines would you
suggest in filter selection?

how important is activated charcoal (AC) in a filter if main tank is
filled from municiple water supply : does AC (or other _______ (?)/
finer micron ratings) rank higher in importance when improvising water
supply ?
Activated carbon is used for decolorization, odor control, chlorine
reduction, etc. ab/adsorbtion. Its best to use such filters when
*filling* the tank but you need to have sufficient 'contact time' of the
fluid within the filter matrix so the absorbtion process can take place.
Unless the filter manufacturer specifies the flow rate, use such filters
as s-l-o-w as possible to gain maximum residence/contact time of the
fluid inside the filter. Use of a carbon packed filter as on onboard
installation is the least effective: 1. the carbon will strip (by
chemical equilibrium) most of any chlorine you add to the water as a
sanitization agent. 2. activated carbon is very good nutrient source for
bacteria and other microorganisms and will promote a large bloom of bio
growth.


My Irwin 37cc is the perfect boat for catching rain off the deck, the
previous owner bought but never installed the valves, figuring the
water we catch on deck will not be of the quality delivered from our
municiple supply and when cruising captured rain will be our greatest
supplement;
Rain water is probably better than most municipal supply (from surface
water) as the zoocysts, bacterial and viral load, heavy metals, etc. is
greatly reduced - just filter out the ambient/airborne molds/mildews and
a few airborne bacteria, airborne particulate and all should be OK. Just
remember that just about every rain drop forms on a microscopic piece of
dirt, etc.

aside from treating tank/captured water with bleach; if I
added a circulation path to the water system what guidelines would you
suggest in filter selection?
For a recirc. system that has a high flow pump, 5 to 10 micrometers
would probably be OK, then into a single pass filter of 1 micrometer
rating of at least 98-99% efficiency before charging the main storage tank.