Puritab temperature adjustment

Quixoticgeek

Full Member
Aug 4, 2013
2,476
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Europe
Now it's getting colder I've taken my sawyer filter out my pack and am relying on Oasis puritabs for water treatment. I know that as temperature drops I need to give them more time to work, but wondered if there's a rule of thumb for how long, a sort of for every x below 20C, add y minutes.

Thanks

Julia
 

Bishop

Full Member
Jan 25, 2014
1,572
520
Inside the wire, Llanelli
Disclaimer - I am not a chemist or microbiologist, so grab a coffee there's a some reading. This is what I found so far...

Oasis puritabs according to Hydrachem the people that make them will disinfect water making it suitable to drink in just ten minutes. source-1
The thirty minute rule is for areas where Schistosoniasis (Bilhalzia) is prevalent. (I had to look that one up it's a parasitic worm that lives in fresh water in subtropical and tropical regions)

I'm also assuming these figures are for water at normal temperate daytime temperatures and there's not too much crud in suspension

Now If I'm reading it right the chlorine dosage of a basic 'Oasis' tablet in one litre of water is 10ppm (parts per million)
and according to this document The Fundamentals of Chlorine Chemistry and Disinfection (1962!) that should kill almost everything at temperatures just above freezing after forty minutes.
Now the bad news, the E.histolyica parasite is just outside the kill zone for this concentration & time at 0-5 degrees centigrade according to this research.

Screenshot-2017-10-13Chlorine Talk Water Supply 12-13-07 handout ppt - cl2chemistry pdf.jpg
 

Hammock_man

Full Member
May 15, 2008
1,257
263
kent
On a similer note, does anyone have the specs for the water tablets that are found in rat packs?
O.K. I have found the people who make the tablets and got the info
 
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Janne

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Feb 10, 2016
12,368
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Grand Cayman, Norway, Sweden
Chlorine tablets work well in any temperature water ( liquid) if the recommended time is adhered to in Europe. I guess the same applies in other areas, including subtropical and tropical areas.

UN has many projects where they purify local water with tablets, they are widely distributed.

(As you can buy beer in most tropical and sub tropical areas, I would not worry about making dirty water safe there......)
 
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oldtimer

Full Member
I don't know about the Caymans, but when I lived in the Bahamas many years ago, beer was so expensive that it was cheaper to drink rum. I was told that the reason that beer was expensive was that it could not be brewed there because of the shortage of water. The water was mostly what was drawn from the porous rock and too deep a well hit the salt water below the fresh. No rivers or lakes there apart from brackish lagoons and keeping the golf course greens in good condition for the tourists a higher priority than drinking water for the inhabitants! We used to add chlorine bleach to tap water for drinking. Fortunately rum was cheap and plentiful and my younger son still prefers rum to any other drink!
 

Janne

Guest
Feb 10, 2016
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Grand Cayman, Norway, Sweden
Our water here is all desalinated. Our local brewery is using it, they make some good beers and an ale too.

Not the best, but it is fresh. Importing quality beers inside a hot container across the ocean does not improve the quality.

Jamaican Red Stripe is good. They apparently also brew Heineken. Some say they do, some say they do not.

I do not check prices on Essentials ( beer is an essential food group) but I think a bottle of European beer is around USD 2.50 - 3 in the alco shops?

The desalinated water here tastes better than what we had in my area in East Sussex. Expensive though. But my garden is a no-watering garden. My water bill is around USD 60 a month during summer and 100 a month during dry season, which is very good.
 
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Quixoticgeek

Full Member
Aug 4, 2013
2,476
5
Europe
Chlorine tablets work well in any temperature water ( liquid) if the recommended time is adhered to in Europe. I guess the same applies in other areas, including subtropical and tropical areas.

Does the recommended time not change with Temp?

UN has many projects where they purify local water with tablets, they are widely distributed.

(As you can buy beer in most tropical and sub tropical areas, I would not worry about making dirty water safe there......)

Yes, because beer flows from springs in the tropics...

J
 

Janne

Guest
Feb 10, 2016
12,368
2,262
Grand Cayman, Norway, Sweden
Does the recommended time not change with Temp?



Yes, because beer flows from springs in the tropics...

J


No time adjustment as far as I remember. As it is a chemical doing the sterilisation, not an enzyme.

Robson Valley is the expert here, maybe he can chime in ?

You can find good beer everywhere here. As long as there is one guy, there is beer. And trust me, the beer is good.
We are not talking Carling or the US made dishwasher grey water here....