__NOTOC__{{Language-box|english_link= Slow sand filter | french_link= Coming soon | spanish_link= Coming soon | hindi_link= Coming soon | malayalam_link= Coming soon | tamil_link= Coming soon | swahili_link=coming soon | korean_link= Coming soon | chinese_link=缓沙过滤器 | indonesian_link= Coming soon | japanese_link= Coming soon }}[[Image:Icon_biosand.png|right|80px]][[Image:slow sand filter.jpg|thumb|right|300px200px|EELRCA water project: slow sand filter, Yakbe, CAR. Photo: [http://www.travelblog.org/Photos/2411254 Travelblog.org]]]
The slow sand filter ensures a simultaneous bacteriological and physical improvement in water quality comparable to the natural percolation of water through underground strata. Jal-TARA is standardized in 1000 litres water tank with the output water supply of 2500 – 3000 litres per day. The filters contain pebbles and sand of different sizes. System is provided with a synthetic fabric filter designed with advanced technique of fabric protection. The system can be fed under gravity flow or through conventional pumps or operated by solar photo-voltaic.
===Suitable conditions===
Slow sand filters are more suitable for low-turbidity water or water that has been pre-filtered. They are used to remove algae and microorganisms, including protozoa, and, if preceded by microstraining or coarse filtration, to reduce turbidity (including adsorbed chemicals). Slow sand filtration is effective for the removal of some organics, including certain pesticides and also ammonia.
|-
! width="50%" style="background:#efefef;" | Advantages
! style="background:#ffdeadf0f8ff;" | Disadvantages
|-
| valign="top" | - Improves water clarity substantially <br>
}}
===Construction, operations and maintenance===[[Image:slow sand filter diagram.jpg|thumb|right|300px200px|Slow sand filter mechanics. Diagram: WHO.]]
The top 5 to 10 cm of wet sand must always be under oxygen rich water. Therefore, the system needs continuous water flow
The plastic parts last up to 5 years.
==Cost=Costs===
{{Treatment_Cost2
|CapCost= Rs. 80.000 = ~ € 1.300
==Field experiences==[[Image:Jal-TARA filter.jpg|thumb|right|300px200px| Jal-TARA filter]] ==Reference manuals, operations and maintenance==
===Manuals, videos, and links===
* '''Video #1''': A quick look at roof water harvesting using a slow sand filter combined with a diverter. This is an overview of the procedure and a demonstration of a working system.
* '''Video #2''': How to build a slow sand water filter using a 55 gallon barrel. This shows the actual assembly of a slow sand filter very similar to the one shown in the first video.
{|style="font-size: 125%"
|-
|{{#ev:youtube|BaCOlRlw3K4|200|auto|<center>Rainwater harvesting <br>with a slow sand filter</center>}}
|{{#ev:youtube|S-_RDB3RvSY|200|auto|<center>Rainwater harvesting with <br>a slow sand filter: PART 2</center>}}
|}
===Acknowledgements===* [http://wwwdocs.googlewatsan.comnet/Downloaded_Files/PDF/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CGcQFjAB&url=http%3A%2F%2Fwhqlibdoc.who.int%2Fpublications%2F2011%2F9789241548151_engWHO-2011-Guidelines.pdf&ei=0Za6T7rBFMKZiQLZhOH1Bg&usg=AFQjCNGx2Q3Rc5yFmbygAIgmJOjg5CSp7g&sig2=8YRhyKpjfeGy8xqp9j8X4Q Guidelines for Drinking-water Quality.] or ([http://apps.who.int/iris/bitstream/10665/44584/1/9789241548151_eng.pdf alternative link]). Fourth edition. WHO, 2011.