<html><body><div style="color:#000; background-color:#fff; font-family:tahoma, new york, times, serif;font-size:12pt">All-<br>No, No, No! Storing water in a dark container does NOT kill pathogenic bacteria or other organisms! Nor does refrigeration or even freezing. E Coli and other bacteria can survive for weeks in a cold dark environment. Heating, filtration, UV disinfection and chemical treatment (chlorine or other) are the only recommended methods I'm aware of for drinking water decontamination. <br>Bacteria tend to cling to particles in the water so allowing it to settle or adding a flocculating agent can sometimes help a little. Particulate material in the water also blocks UV penetration and thus makes solar (UV) disinfection less effective.<br>Part of the problem with bore wells and similar systems is that they become readily contaminated by misuse and need to be monitored. I'm aware of a diarrheal outbreak in Kenya
caused by a contaminated well, and so we recommend frequent testing of community water sources. We supply the testing materials to trained health workers and others at no cost so that they can safely and accurately monitor local water supplies. For the average family it's better to just assume contamination and develop the habits of drinking water purification. <br>The WAPI's (Water Pasteurization Indicator's) that Jeff Holiman and others mentioned cost $7.00 each on the Solar Cookers International website, but really only cost about $.05 to manufacture. Where the rest of the money goes, I know not. Bob Tait of Clackamas, Oregon makes and distributes thousands of them for free to various missionary groups and other non-profits. My only point with Bob is that I believe they should used as part of a general program that supports various health and sanitation practices including safe latrines, hand washing and
clean water storage. These practices can be adapted to local cultural practices and should include follow up and support.<br>Our free training programs include teaching accurate testing and interpretation of water samples using the 3M petrifilm methods and a second fluorescent confirmatory assay called Colilert. We also train participants in the use of the WAPI's, and other disinfection methods and in the construction of simple solar and biomass stoves that that families can use to heat their water and to cook. The workshops usually take a day and a half but for efficiency sometimes can be squeezed into a day. If there is enough interest I could organize one here in Portland or in some other site.<br>Tom Carter<br><br><div><span><br></span></div><div><br></div> <div style="font-family: tahoma, new york, times, serif; font-size: 12pt;"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div dir="ltr"> <font
face="Arial" size="2"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Crispin Pemberton-Pigott <crispinpigott@gmail.com><br> <b><span style="font-weight: bold;">To:</span></b> 'Tom Carter' <tom@aguapuraparaelpueblo.org>; 'Discussion of biomass cooking stoves' <stoves@lists.bioenergylists.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Thursday, February 14, 2013 11:59 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> RE: [Stoves] A simple water sterilization technique<br> </font> </div> <br><div id="yiv2014503185"><style><!--
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--></style><div><div class="yiv2014503185WordSection1"><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Dear Friends</span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">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. </span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">In contrast, nearly everyone in peri-urban and rural Indonesia boils their drinking water. Completely different situation, for which stoves are required.</span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Regards</span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",
"sans-serif";color:#1F497D;">Crispin</span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></div><div class="yiv2014503185MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></div><div><div><div class="yiv2014503185MsoNormal" style="background:white;"><span style="font-family:"Tahoma", "sans-serif";color:black;">Jeff-</span></div></div><div><div class="yiv2014503185MsoNormal"><span style="font-family:"Tahoma", "sans-serif";color:black;">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.</span></div></div><div><div class="yiv2014503185MsoNormal"><span style="font-family:"Tahoma", "sans-serif";color:black;">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.</span></div></div><div><div
class="yiv2014503185MsoNormal"><span style="font-family:"Tahoma", "sans-serif";color:black;">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.</span></div></div><div><div class="yiv2014503185MsoNormal"><span style="font-family:"Tahoma", "sans-serif";color:black;">Tom Carter</span></div></div><div><div class="yiv2014503185MsoNormal"><span style="font-family:"Tahoma", "sans-serif";color:black;"><a rel="nofollow" target="_blank" href="http://us-mg4.mail.yahoo.com/neo/aguapuraparaelpueblo.org">Agua Pura Para El Pueblo</a></span></div></div></div></div></div></div><br><br> </div> </div> </div></body></html>