[[Image:Building a horizontal cistern.jpg|thumb|right|300px200px|Building a horizontal cistern. Photo: from the video: [http://vimeo.com/8452760 How to build a horizontal cistern]]][[Image:roman cistern.jpg|thumb|right|300px200px|A Roman cistern back from a long time ago. Used as a water holding "tank". Photo: [http://www.danheller.com/images/Europe/Turkey/Lydea/Slideshow/img3.html DanHeller.com].]][[Image:horizontal cistern lid.jpg|thumb|right|200px|Building the lid for a horizontal cistern. Photo: from the video: [http://vimeo.com/8452760 How to build a horizontal cistern]]][[Image:horizontal cistern mud.jpg|thumb|right|200px|Adding a smooth mud wall to the inside of a horizontal cistern. Photo: from the video: [http://vimeo.com/8452760 How to build a horizontal cistern]]]__NOTOC__ <small-title />
The horizontal cistern is a variation of the regular EMAS vertical design, more suitable for ground where it is not possible to dig deep.
EMAS is the acronym for Escuela Móvil de Agua y Saneamiento (Mobile School for Water and Sanitation), in Bolivia, whose director, Wolfgang Eloy Buchner, developed the EMAS pump in the 1990s. EMAS is not only the name of the mobile school for water and sanitation, but also a whole technical and social concept of water and sanitation which includes rain water harvesting, solar water heaters, windpower, hydraulic rams, water treatment, small tanks and sinks, a variety of hand and foot pumps, and ferrocement tanks. The aim of the technologies and systems is to achieve the necessary supply of drinkable water, and water for micro irrigation in rural and sub urban areas.
===Suitable Conditions===
The Horizontal cistern is suitable in areas with rocky ground, where it is not possible to dig deep enough for a vertical cistern.
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! width="50%" style="background:#efefef;" | Advantages
! style="background:#ffdeadf0f8ff;" | Disadvantages
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| valign="top" | - A water truck can simply let water fall into the tank by gravity – no pump required <br>
- Water can be directly pumped into a household storage tank with an EMAS pump <br>
- 7000l 7000L tank with pump costs US$ 70$ in Bolivia <br>
- Tank occupies little space – is less noticeable <br>
- Easy to filter roofwater before it entering enters the tank <br>- Temperature underground is more constant – cracks are likely <br>
- Does not require ground to be firm, like the vertical cistern. <br>
| valign="top" | - More complicated to build than a vertical cistern <br>
- If the cistern is an open underground tank, contamination (livestock, rainwater runoff carrying pesticides) is more probable, therefore a lid is recommended.<br>
- Cracks are likely and harder to detect.
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===Resilience to changes in the environment===
====Drought====
For more information on drought: [[Resilient WASH systems in drought-prone areas]]
===Construction, operations and maintenance===
It is operated in the same way as a vertical cistern.
The horizontal cistern is around 1m x 3m large, and can be up to 2.5m deep.
It consists of two sections, one which is slightly deeper, and round, similar to the vertical cistern. This is done so there is room for a pump. The other is the vault, which is long, and less deep.
First a hole is dug for the cistern. It should be less deep in the area where the vault is, and deepen deeper on one end, where the pump will be. Then the arch shaped cover for the vault is manufactured using sticks and mud as a mold. The cover is made of 2 layers of cement, with stones in between. The cement is left to dry for 4 days. The walls of the cistern are then built, with layers of mud and cement of different thicknesses. Then the walls, curbstone, cover and pump are installed in the other section, in a similar way to how it is done with the vertical cistern. ==Costs==
==Field Experiences=Costs= ==Costs can be divided as such: 1/3 = cost of materials; 1/3 = cost of transport, labour, etc.; and 1/3 = cost to cover failures, or replacements.
==Reference manuals=Manuals, videos, and links===* VideoVIDEO: [http://vimeo.com/8452760 How to build a horizontal cistern]The horizontal cistern instructions start at 12:36.
* [http://rainwater-toolkit.net/fileadmin/rwh-material/haury/00_HAUR.pdf The Plate Cistern Project Management and Construction Manual.]
* [http://www.lenntech.com/small-community-water-supplies.htm#ixzz2TsbJyNk6 Water supply in small communities], by Lara Fabrizi. Includes how best to manage the planning, construction, and operation and maintenance of water projects or tanks.
===Acknowledgements===* Buchner, Wolfgang. [http://www.emas-international.de/fileadmin/pics/virtueller_lehrgang/lehrbuecher/water_for_everybody_6_2012.pdf Water for Everybody: A Selection of Appropriate Technologies to be used for Drinkable Water EMAS]. EMAS Water and Basic Sanitation Mobile School. 5th edition, 2006.