[Stoves] Water Disinfection - Mix Boiling Water and Unheated Water to Pasteurize

[Crispin Pemberton-Pigott]

Dear Andrew

The most important question is what do those temps kill: everything that is bacterial.

Spores are a serious problem and prions even worse. Tough little things. They are not really alive and some coat themselves when “challenged”.

>>Low cost WAPI's wax indicators can tell you 70C is achieved visually

>Thanks for that Tony, I too find this interesting and having a means of indicating the certainty of adequate treatment  would reassure me, who drinks, bathes and cleans with water supplied by a pipe with guaranteed levels of hygiene.

There is a long-standing programme to promote the distribution of those devices in low water quality areas.

>We had a  potter who used to contribute, now deceased , his name escapes me, who made pottery filter jugs which he precipitated a thin late of silver in as a bactericide

Those work very well and remove the need to boil.  Also a slow sand filter (properly managed which means having two in parallel) so, ditto. We always added chlorine as a precaution, with 2 ppm of free Cl at the end of the longest line at the last tap. That takes care of pipeline contamination.

Caution for those planning to test the bacteria after any processing – read how to do this sampling well. You have to “flame” all the containers and the tap before taking the sample. Contamination is very easy. I would not believe a positive result collected by an untrained staffer.

>Interesting chart Crispin but it doesn't show what each of those treatments achieve, or do they all do the same thing to all microbes?

All microbes usually found in water.  Surely there are exceptional cases? Deep sea critters? More escapes heat than I assumed.  It helps to know what is in the water before starting to test a treatment regimen.

>What temperature does kill anthrax, tetanus and botul;sm spores?

Looks like 150 C.  They are no so much killed as destroyed. I think they are not alive in the first place.  “Life” has a loose definition.  A great many water-borne pathogens are killed simply by being in a fully darkened tank for three days. If you have no treatment available at all for washing water, keep it in a storage system that excludes all light. Nearly everything dies (but not all, of course).  Such simple treatment will kill bilharzia, for example.

Drink safe…
Crispin
Ex-Clerk of Works, Rural Water Supply Program, Hhohho District, later Lubombo District, in (then) Swaziland – one of the lighter squares on the board of my chequered career
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