Editing Cloth filter

{{Short description|Method to decontaminate drinking water}}

{{about|decontamination of drinking water||cheesecloth}}

{{for|reusable coffee filters made of cloth|cloth coffee filter}}

[[Image:Washing Utensils And Vegetables.png|Women at a village pond in [[Matlab, Bangladesh]] washing utensils and vegetables. The woman on the right is putting a sari filter onto a water-collecting pot (or [[Kalasha|kalash]]) to filter water for drinking.|thumb|240px]]

A '''cloth filter''' is a simple and cost-effective [[appropriate technology]] method for reducing the contamination of drinking water, developed for use mainly in [[Bangladesh]]. Water collected in this way has a greatly reduced [[pathogen]] count. Though not always perfectly safe, it is an improvement for poor people with limited options.

Filtering water to free it from micro-organisms has been an age-old practice among [[Jains]] who carefully remove the micro-organisms in the cloth through filtered water in order to follow doctrine of [[Ahimsa]] or non-violence, preventing pain to any living creature.

The method used in Bangladesh is as follows: cloth is folded to make four or eight layers and the folded cloth is placed over a wide-mouthed container used to collect surface water. After use, it is usually sufficient to rinse the cloth and dry it in the sun for a couple of hours. In the [[monsoon]] seasons, it may be advisable to use a cheap [[disinfectant]] to decontaminate the material.

The preferred cloth is used cotton [[sari]] cloth. Other types of clean, used cloth can be used with some effect, though the effectiveness will vary significantly. Used cloth is more effective than new cloth, as the repeated washing reduces the space between the fibers.<ref>{{cite news |author=Moss J |title=Cloth Filters Fight Cholera |work=Development Report |publisher=Voice of America |date=January 27, 2003 |url=http://www.manythings.org/voa/03/030127dr_t.htm |url-status=dead |archiveurl=https://archive.today/20120804132758/http://www.manythings.org/voa/03/030127dr_t.htm |archivedate=August 4, 2012 }}</ref>

In [[sub-Saharan Africa]] where [[guinea worm]] infections ([[dracunculiasis]]) are endemic, infection is prevented by use of a nylon mesh with pore size of approximately 150 [[μm]] to filter out the copepods that host the parasite.<ref name="original">{{cite journal |vauthors=Colwell RR, Huq A, Islam MS |title=Reduction of cholera in Bangladeshi villages by simple filtration |journal=Proc Natl Acad Sci USA |volume=100 |issue=3 |pages=1051–5 |date=February 2003 |pmid=12529505 |pmc=298724 |doi=10.1073/pnas.0237386100 |bibcode=2003PNAS..100.1051C |display-authors=etal|doi-access=free }}</ref><ref>{{cite news |title=Fighting the 'fiery serpent' in Sudan |url=http://www.abc.net.au/news/stories/2008/06/06/2267262.htm |agency=Reuters |work=ABC News |publisher=[[Australian Broadcasting Corporation]] |date=June 6, 2008 |quote=The [[Carter Center]] distributes cloth filters and plastic drinking pipes with gauze at one end to block the larvae.}}</ref><ref>{{cite journal |vauthors=Hopkins DR, Ruiz-Tiben E, Diallo N, Withers PC, Maguire JH |title=Dracunculiasis eradication: and now, Sudan |journal=Am. J. Trop. Med. Hyg. |volume=67 |issue=4 |pages=415–22 |date=October 2002 |pmid=12452497 |url=http://www.ajtmh.org/cgi/pmidlookup?view=long&pmid=12452497 |quote=More than 278,000 cloth filters for household use in preventing the infection were distributed in Sudan in 1995 (compared with 93,000 the year before), and approximately 600,000 or more have been distributed each year since then. In 2001, however, in addition to distributing nearly 850,000 filters for household use, more than 7.8 million pipe filters were also distributed throughout endemic areas ....

|doi=10.4269/ajtmh.2002.67.415 |doi-access=free |citeseerx=10.1.1.549.9398 }}</ref>

An old folded cotton sari creates a smaller effective mesh size (approximately 20-μm). This should be small enough to remove all zooplankton, most phytoplankton, and thus a large proportion of the cholera in the water (99%, according to laboratory studies). However, the nylon net with the larger mesh size was found to be "almost equally effective."<ref name="original"/>

The cloth filter provides less than ideal purification on its own - usually filtering is an initial step, to be followed by further disinfection. However, where there are no other options, water professionals may consider that it is "of course, better than nothing" <ref>{{cite journal |author=Hogan J |title=Old clothes filter out cholera |journal=[[New Scientist]] |date=13 January 2003 |url=https://www.newscientist.com/article.ns?id=dn3258}}</ref>

The cloth filter has been studied and reported on by [[Rita R. Colwell|Rita Colwell]] and [[Anwar Huq]] from the [[University of Maryland Biotechnology Institute]], together with other researchers from the United States and [[Bangladesh]]. They report that: "It is common practice in villages in Bangladesh to use cloth, frequently a flat, unfolded piece of an old sari, to filter home-prepared drinks".<ref name="original"/>

The researchers studied the application of this technique to drinking water, with folded cloth. They studied the pore size of the cloth, the effect of folding the cloth on the effective pore size, the ability of the cloth to remove particles and plankton, as well as the effect on rates of cholera when used in a Bangladesh village.<ref>{{cite journal |first= Anwar |last= Huq |author2=Mohammed Yunus |author3=Syed Salahuddin Sohel |author4=Abbas Bhuiya |author5=Michael Emch |author6=Stephen P. Luby |author7=Estelle Russek-Cohen |author8=G. Balakrish Nair |author9=R. Bradley Sack |author10=Rita R. Colwell.Awabdeh |title= Simple sari cloth filtration of water is sustainable and continues to protect villagers from cholera in Matlab, Bangladesh |journal= mBio |volume=1|issue=1| date=2010 |url= http://intl-mbio.asm.org/content/1/1/e00034-10.full |doi=10.1128/mbio.00034-10 |pmid= 20689750 |pages=e00034-10|pmc=2912662 }}</ref>

{{Reflist}}

*[https://web.archive.org/web/20051109121307/http://www.tve.org/ho/doc.cfm?aid=588 Safe Saris - Bangladesh]

*[https://web.archive.org/web/20030409171403/http://202.136.7.26/news/index.jsp?idDetails=41 Sari filter stops cholera], with photo. [[ICDDR,B]] website.

*[https://www.nsf.gov/news/speeches/colwell/rc02_hippocratic/sld025.htm Photo showing woman using sari to filter drinking water] - Source: Dr. Rita Colwell [https://www.nsf.gov/news/speeches/colwell/rc02_hippocratic/tsld025.htm]