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water:start [2022/02/17 14:10] frater_secessus [Water] |
water:start [2022/08/14 19:29] frater_secessus moved purification to own page |
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It is far easier to //use less water// than to haul, store, and dispose of gray water. | It is far easier to //use less water// than to haul, store, and dispose of gray water. | ||
- | ===== Water Filtration ===== | ||
- | [[https:// | ||
- | Mechanical filtration has become more common and less expensive. | ||
- | The main drawback of filtration are clogging (addressed by adquate pre-filtration) and relatively slow filtration rate. Look for filters that can be gravity fed so the filtration time isn't tiresome. | ||
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- | * 1-micron filters will filter protozoa like giardia spores and Cryptosporidium out of clear water.((https:// | ||
- | * 0.1-micron will filter all waterborne enteric bacteria from clear water | ||
- | * Consumer-grade filtration will not remove viruses because of their tiny size. | ||
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- | The CDC points out the difference between nominal and absolute((or " | ||
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- | === Fabric filtration === | ||
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- | Much sediment can clear itself if allowed to rest; Let the water sit still for 30-60 minutes, then pour or siphon off the top and leave the sediment behind. | ||
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- | Alternately you can strain from coarse to fine: through a strainer then a coffee filter, for example. | ||
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- | - sieve | ||
- | - bandana, cloth, or paper towel | ||
- | - coffee filter | ||
- | - actual water filter | ||
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- | Note that filtration through layered fabric is much better than nothing. | ||
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- | > a filter made of four layers of worn cotton material held back more than 99 percent of all cholera bacteria - using more layers or newer cloth slowed water collection too much.((https:// | ||
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- | Both saris and coffee filters have about a 20-micron pore size: | ||
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- | > Typically coffee filters are made up of filaments approximately 20 micrometres wide, which allow particles through that are less than approximately 10 to 15 micrometres((https:// | ||
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- | The best we should assume for with such //ad hoc// filtration is a pathogen // | ||
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- | Further reading: | ||
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- | ---- | ||
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- | ===== Water Purification ===== | ||
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- | It is possible to disinfect suspect water by several means; it is //not// practical to purify water that is chemically or mineralogically tainted. | ||
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- | When possible, multiple approaches should be used on the water. | ||
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- | ==== Heat ==== | ||
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- | Heat is an effective way to kill waterborne pathogens. | ||
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- | > Sterilisation of water (killing all living containments) is not necessary to make water safe to drink. For example, boiling may not be effective against bacterial spores such as Clostridium which can survive at 100°C (212°F), however, as Clostridium is not a waterborne enteric (intestinal) pathogen, ingestion will not cause infection. | ||
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- | > All waterborne enteric pathogens are quickly killed above 60°C (140°F), therefore, although boiling is not necessary to make the water safe to drink, **the time taken to heat the water to boiling is usually sufficient to reduce pathogens to safe levels**. Allowing the boiled water to cool slowly will also extend the exposure of waterborne enteric pathogens to lethal temperatures. | ||
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- | Typical times at temperature: | ||
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- | * 212F (100C, boiling at sea level) - 0 minutes | ||
- | * 158F (70C) - 1 minute. | ||
- | * 145F (63C) - 30 minutes to achieve pasteurization.((https:// | ||
- | * 130F (55C) - 10 minutes to kill giardia((https:// | ||
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- | Given that information, | ||
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- | ==== Chemical treatment ==== | ||
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- | Chemical treatments require no power making them especially useful offgrid. | ||
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- | The most famous treatment is **chlorine bleach**. | ||
- | Note that bleach purfication does not reliably kill Cryptosporidium. | ||
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- | Bleach is cheapest by the laundry bottle but is also [[https:// | ||
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- | [[https:// | ||
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- | === Flocculation === | ||
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- | Hybrid chlorinating-flocculating chemicals such as [[http:// | ||
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- | === SODIS === | ||
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- | SOlar water DISinfection (SODIS) uses sunlight to improve water quality.((https:// | ||
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- | Efficacy: | ||
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- | Optimal function may be found by placing small-diameter bottles in a solar oven. This will enhance UV collection and heating. | ||
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