[[Image:Planted_soil_filter_icon.pngjpg|right]]
Planted soil filters, also referred to as constructed wetlands or reed bed systems, are natural systems treating solid-free wastewater. This can be pre-treated wastewater from a flush toilet or faecal wastewater from a urine diversion toilet, either combined with wastewater from the kitchen and bathroom, or separate from it. A planted soil filter, preceded by a settling and watertight storage tank, consists of a sand and gravel matrix (sealed at the bottom) planted with wetland plants like reeds. Solid free wastewater is discharged from the storage tank on top of the filter or though an underground inlet-system and flows through (vertical) the filter. Horizontal-flow soil filters are commonly found, and easier to construct than vertical flow filters, but they are less efficient at eliminating nitrogen. Wastewater is treated through several processes, in which bacteria play an important role. After treatment, the effluent can be discharged into surface water, used for irrigation or groundwater recharge.
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! width="50%" style="background:#efefef;" | Advantages
! style="background:#ffdeade9f5fd;" | Disadvantages
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| valign="top" | Removes pathogens from wastewater.<br>
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=== Costs ===
* Costs can vary greatly, and depend, among other factors, on local availability of gravel, the kind of sealing and the cost of land.
* Operational costs 7000 inhabitants US$ 1.17 per person, per year (Syria, 1999).
=== Applying conditions ===
<ul>
<li>If planted soil filters are applied in hot climates with a continuous growing season, wetland biomass can be harvested. </li>
</ul>
=== External links ===
* General information about Planted soil filter [http://www.bodenfilter.de/engdef.htm www.bodenfilter.de/engdef.htm ]
* General information [http://www.constructedwetlands.org www.net/ constructedwetlands.org net ]
* General information [http://www.gtz.de/ecosan www.gtz.de/ecosan ]
* General information [http://www.sandec.ch www.sandec.ch ]
