[Stoves] A simple water sterilization technique

[Crispin Pemberton-Pigott]

Dear Friends

 

Keeping water in the total dark for 3 days kills quite a lot of things
including Bilharzia. When I worked in Rural Water Supply in Swaziland we
provided covered tanks with more than 3 days storage on most systems for
this reason (in the lowveld). We also used dosing boreholes with
chlorination occasionally (always when new) and precautionary chlorination
using bypass jets on pumped systems to get a 2 ppm level at the last
standpipe. No one boiled water to purify it in those days. 

 

In contrast, nearly everyone in peri-urban and rural Indonesia boils their
drinking water. Completely different situation, for which stoves are
required.

 

Regards

Crispin

 

 

Jeff-

Thanks for the post.  Yes, it's true that pasteurization at 65C kills all
pathogenic bacteria and viruses, as well as worms and cysts.  I don't
recommend "feeling it with your hand" however as even a 10 degree lower
temperature will have a much lower effectiveness.  As you note, a wax
indicator developed by Dr. Robert Metcalf accurately and safely demonstrates
when the water is pathogen free.  We distribute them at no cost to families
and instruct them on their use.  Filtration through a clean cloth probably
helps a little, as does letting the water settle, but is not necessary for
pasteurization.  Some methods that use solar UV disinfection do require
clean water and clear PET water bottles for effectiveness.  They also take
longer, lack an end point and have inconsistent results and for that reason
we don't recommend them.

The last step is keeping safe water safe, by storing it in clean containers
with small openings so that people cannot recontaminate it by dipping in
with dirty containers or hands.

I'm going to give a water testing and water pasteurization workshop here in
Portland in the next months if anyone is interested in being trained.

Tom Carter

Agua Pura Para El Pueblo
<http://us-mg4.mail.yahoo.com/neo/aguapuraparaelpueblo.org> 

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