Wow, what an interesting fact that turbidity should not exceed 30 NTU. Don't get me wrong I really appreciate your, work but I guess very rarely will people have a nephelometer at hand or can interpret the values. Why not make it easy and say if you can't see through the water than you have to put through filter first, because only reasonably clear water can be disinfected by UV. This might not be very scientific but it's so plain simple that people can understand it. Keep up with the good work so! —The preceding unsigned comment was added by (talkcontribs) 11:13 1 sep 2010

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Enjoy, --Lonny 00:21, 2 September 2010 (UTC)
That's right, that an NTU value isn't useful to ordinary people. Unfortunately saying the water must be "clear" is subjective and context dependent. See how clearly, through how much water, with how bright a light? And if they really can't see through it, I suspect that's much too murky - I think the guideline will need to be tighter than that.
Perhaps someone can explain it in a way that it will be safe and easy to follow.
SODIS produced pieces of paper with their logo printed in varying degrees of faintness. Held behind bottles of a standard size, which of the logos are visible through the water determines whether it's clear enough, and helps work out how long it needs in the sun (extremely clear water needs less time than slightly turbid water.
I wish we could provide something on the wiki to be printed, to do this job. But that would depend on the strength of color from the printer, and I don't know how to overcome that. Any ideas? --Chriswaterguy 09:05, 2 September 2010 (UTC)