__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:Jal-TARA slow sand filter.jpg|thumb|right|250px200px| Jal-TARA 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. {{procontable | proborder="1" cellpadding="5" cellspacing="0" align="center"|-! width="50%" style="background:#efefef;" | Advantages! style="background:#f0f8ff;" | Disadvantages|-| valign="top" | - Improves water clarity substantially <br>
- Requires no chemicals <br>
- Easy to install at any site in rural, urban, semi-urban and remote areas. <br>
- Filter can be maintained by the members of the community thus creating livelihood options <br>
- Long term benefits and low recurring costs <br>
| convalign= "top" | - Requires ascertaining the quality of the raw water and normally cannot be applied to water at low temperatures, with high turbidity levels and/or very low nutrient levels <br>- Attitudinal An attitude change might be needed (belief system that water is not clean without chemicals)<br>
- Relatively high initial cost <br>
- Requires electricity/generator <br>
|}}
{{Potential_Treatment_Capacity_table
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===Construction, operations and maintenance===[[Image:slow sand filter diagram.jpg|thumb|right|200px|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.
==Cosst=Costs===
{{Treatment_Cost2
|CapCost= Rs. 80.000 = ~ € 1.300
|m3Cost= € 0,68
}}
These costs assume the lifetime is 15 years with daily production of 2.750 litres; O&M and salary included; salary is based on 1 working day of operator, assuming an average gross annual income of € 500 in developing countries.
==Field experiences==
[[Image:Jal-TARA filter.jpg|thumb|right|200px| Jal-TARA filter]] ==Reference manuals=Manuals, videos, operations and maintenancelinks===* '''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://docs.watsan.net/Downloaded_Files/PDF/WHO-2011-Guidelines.pdf Guidelines for Drinking-water Quality.] or ([http://apps.who.int/iris/bitstream/10665/44584/1/9789241548151_eng.pdf alternative link]). Fourth edition. WHO, 2011.