Thanks for this clarification Carl. There's obviously a discrepancy
between what is stated in Wiki and what is stated on the LifeStraw
packaging.
If the LifeStraw can filter out water particles down to 0.2 micron, it
would indeed filter out nearly all bacteria, amoeboid protozoans and some
viruses . But my concern still remains with respect to viruses, because
the size range of many of them is 0.005 to 0.3 micron. Perhaps those
viruses that occur in potenial drinking water are among the larger
viruses (>0.2 micron across)?
Stephen Ambrose
BTW Stephen, I have just looked at the packaging of my LifeStraw and
it says that LifeStraw filters out particles down to 0.2 microns. Be
happy to send you a scan of the packaging. But then again Google knows
best.
Cheers,
Carl Clifford
On 09/09/2011, at 3:02 PM, Stephen Ambrose wrote:
Most viruses are within the 5 to 300 nanometers (5 to 300 millionths
of a
millimetre) size range.
Most bacteria range in size from 0.2 to 2.0 microns (0.2 to 2.0 one
thousandths of a millimetre)
According to Wikipedia, Lifestraw filters out water particles that are
as
small as 15 microns.
Amoebozoa vary greatly in size, but many are only 10 to 20 microns
across.
However, others are several 100s microns across.
Based on this information, it would appear that the Lifestraw would
not be
very reliable in filtering out waterborne viruses and bacteria or some
protozoans from drinking water.
Stephen Ambrose
Ryde NSW
-----Original Message-----
From:
On Behalf Of John
Leonard
Sent: Friday, 9 September 2011 1:24 PM
To: Birding-aus
Subject: Re: [Birding-Aus] LifeStraw
Sounds like a great idea, however although it will "filter out a
minimum of 99.9% of bacteria, viruses and protozoans" presumably it
wouldn't do anything about the chemical pollution of water, which
might be a problem in intensively farmed areas.
John Leonard
On 9 September 2011 12:58, Carl Clifford
wrote:
> Dear B-A,
>
> I have recently come across LifeStraw
> , a small (22cm x
> 3.5cm),
> lightweight (approx 30g) tube, with a mouth-piece at one end. It will
filter
> out a minimum of 99.9% of bacteria, viruses and protozoans. With a
> LifeStraw, you can safely drink water from sources which you would
normally
> hesitate to wash in. A personal LifeStraw will purify up to 1000
> litres of
> water ( or to put it into context, the equivalent to one pallet of
> bottled
> water). There is also a "family" LifeStraw, which has a grater flow
> rate
and
> is capable of purifying up to 18,00 litres of water, which would be
> useful
> for use in semi-permanent camps.. While our town water supplies are,
> usually, drinkable, having to cart your own water everywhere can be
> a bit
of
> a pain. Being able to safely drink water from just about any creek,
> dam or
> water-hole, does have its advantages, especially if you are stuck
> out in
the
> bush somewhere. A useful thing to add to your emergency kit.
> Unfortunately
I
> don't think it will make bore water any more palatable.
>
> I bought a couple from the local agent
> , cost $20.95 + p&p. I am
> going to
> Sabah next month and will try mine out in a variety of waters. It
> will be
> interesting to see what the Kinabatangan water tastes like.
>
> Profits from sales of LifeStraw are used to subsidise the
> distribution of
> LifeStraw to individuals and communities in the third world. A nice
> idea,
> buy one and reduce your own water supply costs when birding and help
> save
> the lives of others.
>
> I have no affiliation commercial or otherwise with LifeStraw, apart
> from
> being a customer who thinks it is a brilliant concept.
>
> Cheers,
>
> Carl Clifford
>
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>
--
John Leonard
Canberra
Australia
I want to be with the 9,999 other things.
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