reed:reed_beds

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reed:reed_beds [2025/12/05 11:10] – Dave Darbyreed:reed_beds [2026/03/26 18:33] (current) – external edit 127.0.0.1
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-# Reed beds+This topic is part of [[gt:water|Water & sewage]]. 
 +====== Reed beds ======
  
  
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-## What are reed beds?+===== What are reed beds? =====
  
 In a low-impact context, they’re wastewater treatment systems that use growing wetland plants as the active component in getting effluent clean enough to discharge back into the receiving environment. Alternately called treatment wetlands, constructed wetlands or reed bed treatment systems, they have the potential to be low-cost, zero energy input, low-tech, high-efficiency systems that can be used to help protect streams and rivers from almost any source of effluent or dirty water. In a low-impact context, they’re wastewater treatment systems that use growing wetland plants as the active component in getting effluent clean enough to discharge back into the receiving environment. Alternately called treatment wetlands, constructed wetlands or reed bed treatment systems, they have the potential to be low-cost, zero energy input, low-tech, high-efficiency systems that can be used to help protect streams and rivers from almost any source of effluent or dirty water.
  
-### How reed beds work+==== How reed beds work ====
  
 Despite appearances to the contrary, reed beds and constructed wetlands work in a very similar way to conventional treatment systems. Primary settlement takes place in a [septic tank](/sept/septic_tanks); secondary aeration is provided by the plants, which draw oxygen down to the roots via the leaves, where it becomes available for aerobic bacteria; tertiary polishing is carried out if the reed bed is built large enough, providing further removal of nitrogen and phosphorus. Despite appearances to the contrary, reed beds and constructed wetlands work in a very similar way to conventional treatment systems. Primary settlement takes place in a [septic tank](/sept/septic_tanks); secondary aeration is provided by the plants, which draw oxygen down to the roots via the leaves, where it becomes available for aerobic bacteria; tertiary polishing is carried out if the reed bed is built large enough, providing further removal of nitrogen and phosphorus.
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 <caption> <caption>
-Yellow flag, or _Iris pseudacorus_, is a common plant in constructed wetlands and reed beds. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)+_Yellow flag, or _Iris pseudacorus_, is a common plant in constructed wetlands and reed beds. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)_
  
 </caption> </caption>
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-The following physical, chemical and biological treatment mechanisms all come into play (see [glossary](/reed/reed_beds) for explanations):+The following physical, chemical and biological treatment mechanisms all come into play (see [glossary](https://www.lowimpact.org/categories/reed-beds/further-info/glossary) for explanations):
  
 - sedimentation - sedimentation
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 - volatilisation - volatilisation
  
-### Different types of reed bed system+==== Different types of reed bed system ====
  
 The terms reed bed and constructed wetland are often used interchangeably, but there are a number of distinct system types within the general category of treatment wetlands. Although these different system types can be used in series on any given project, the design protocol for each type should not be used interchangeably. The different reed bed types are usually categorised as follows: The terms reed bed and constructed wetland are often used interchangeably, but there are a number of distinct system types within the general category of treatment wetlands. Although these different system types can be used in series on any given project, the design protocol for each type should not be used interchangeably. The different reed bed types are usually categorised as follows:
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 <caption> <caption>
-Soil-based constructed wetland section. Source: _Permaculture Guide to Reed Beds._+_Soil-based constructed wetland section. Source: _Permaculture Guide to Reed Beds.__
  
 </caption> </caption>
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 <caption> <caption>
-Horizontal flow gravel reed bed section. Source: _Permaculture Guide to Reed Beds._+_Horizontal flow gravel reed bed section. Source: _Permaculture Guide to Reed Beds.__
  
 </caption> </caption>
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-**Vertical flow (VF) reed beds**: similar in layout to a raised sand polishing filter or stone trickling filter. Vertical flow reed beds have a smaller footprint area than horizontal flow gravel reed beds, so may be more suited to small sites. The VF reed bed consists of c.1m depth of gravel, of progressively smaller particle sizes towards the bed surface. Effluent is dosed over the bed surface either by [pumped feed](/reed/reed_beds) or [gravity dosing mechanism](/reed/reed_beds) and treatment occurs as it trickles down over the gravel media and plant roots. Bear in mind that VF reed beds filled or topped with sand can be prone to blocking unless the exact aggregate grades are used and the correct degree of pretreatment is consistently achieved.+**Vertical flow (VF) reed beds**: similar in layout to a raised sand polishing filter or stone trickling filter. Vertical flow reed beds have a smaller footprint area than horizontal flow gravel reed beds, so may be more suited to small sites. The VF reed bed consists of c.1m depth of gravel, of progressively smaller particle sizes towards the bed surface. Effluent is dosed over the bed surface either by [pumped feed](https://www.lowimpact.org/categories/reed-beds/further-info/glossary) or [gravity dosing mechanism](https://www.lowimpact.org/categories/reed-beds/further-info/glossary) and treatment occurs as it trickles down over the gravel media and plant roots. Bear in mind that VF reed beds filled or topped with sand can be prone to blocking unless the exact aggregate grades are used and the correct degree of pretreatment is consistently achieved.
  
 <WRAP center centeralign> <WRAP center centeralign>
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 <caption> <caption>
-Vertical flow reed bed section. Source: _Permaculture Guide to Reed Beds._+_Vertical flow reed bed section. Source: _Permaculture Guide to Reed Beds.__
  
 </caption> </caption>
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-## What are the benefits of reed beds?+===== What are the benefits of reed beds? =====
  
 With our current global challenges of climate change and species extinction, reed beds and constructed wetlands can offer a zero energy input way to get our sewage clean, and also provide reliable sewage treatment at a time when continuation of reliable ongoing electricity supply to our municipal and domestic sewage systems is not guaranteed, thus helping to preserve the habitat integrity of our rivers, lakes and coastal waters for biodiversity. With our current global challenges of climate change and species extinction, reed beds and constructed wetlands can offer a zero energy input way to get our sewage clean, and also provide reliable sewage treatment at a time when continuation of reliable ongoing electricity supply to our municipal and domestic sewage systems is not guaranteed, thus helping to preserve the habitat integrity of our rivers, lakes and coastal waters for biodiversity.
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 <caption> <caption>
-Newly planted domestic gravel reed bed system for septic tank effluent treatment prior to percolation. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)+_Newly planted domestic gravel reed bed system for septic tank effluent treatment prior to percolation. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)_
  
 </caption> </caption>
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 <caption> <caption>
-Great overview of constructed wetlands and why they are such sustainable systems.+_Great overview of constructed wetlands and why they are such sustainable systems._
  
 </caption> </caption>
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 <caption> <caption>
-Water lilies (Nymphaea alba cultivar) in a constructed wetland pond. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)+_Water lilies (Nymphaea alba cultivar) in a constructed wetland pond. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)_
  
 </caption> </caption>
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 - The gravel media has the potential for clogging if the septic tank isn't properly maintained. One potential solution is to install two septic tanks before the reed bed, or to use a septic tank filter unit at the outlet pipe. Nonetheless, maintenance is a bigger factor for reed beds than for soil-based wetlands. - The gravel media has the potential for clogging if the septic tank isn't properly maintained. One potential solution is to install two septic tanks before the reed bed, or to use a septic tank filter unit at the outlet pipe. Nonetheless, maintenance is a bigger factor for reed beds than for soil-based wetlands.
  
-- If you are using a small [modular unit](/reed/reed_beds) then it is extra important that your [mechanical treatment unit](/reed/reed_beds) is functioning at top efficiency all of the time to ensure that the overall system performs as designed. (Modular units are usually used only for tertiary treatment after a [mechanical aeration unit](/reed/reed_beds)).+- If you are using a small [modular unit](https://www.lowimpact.org/categories/reed-beds/further-info/glossary) then it is extra important that your [mechanical treatment unit](/reed/reed_beds) is functioning at top efficiency all of the time to ensure that the overall system performs as designed. (Modular units are usually used only for tertiary treatment after a [mechanical aeration unit](https://www.lowimpact.org/categories/reed-beds/further-info/glossary)).
  
 - At some stage, the gravel will clog up anyway. Bacteria mass, sediments and plant debris will all contribute to the eventual congestion of the gravel. While soil-based wetlands have an adjustable flow control unit that can simply be raised as sediment levels rise, gravel reed beds will need a complete overhaul every 15 to 30 years depending on influent quality, system size and throughput volumes. - At some stage, the gravel will clog up anyway. Bacteria mass, sediments and plant debris will all contribute to the eventual congestion of the gravel. While soil-based wetlands have an adjustable flow control unit that can simply be raised as sediment levels rise, gravel reed beds will need a complete overhaul every 15 to 30 years depending on influent quality, system size and throughput volumes.
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 <caption> <caption>
-Reed bed mid-construction: upper vertical flow bed followed by lower horizontal flow reed bed, then planted with Phragmites and Iris. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)+_Reed bed mid-construction: upper vertical flow bed followed by lower horizontal flow reed bed, then planted with Phragmites and Iris. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)_
  
 </caption> </caption>
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-**Vertical flow reed beds** are generally used to pretreat effluent entering a horizontal flow reed bed, where a higher quality of effluent is needed in a small space. They can also be effective where good soil percolation characteristics exist, but where a quick burst of treatment is needed prior to discharge to ground. Their main drawback is that a pump is usually needed to provide the required distribution of effluent over the reed bed surface. That said, a [gravity splitter, dosing box or syphon](/reed/reed_beds) may all be used where suitable falls are present.+**Vertical flow reed beds** are generally used to pretreat effluent entering a horizontal flow reed bed, where a higher quality of effluent is needed in a small space. They can also be effective where good soil percolation characteristics exist, but where a quick burst of treatment is needed prior to discharge to ground. Their main drawback is that a pump is usually needed to provide the required distribution of effluent over the reed bed surface. That said, a [gravity splitter, dosing box or syphon](https://www.lowimpact.org/categories/reed-beds/further-info/glossary) may all be used where suitable falls are present.
  
 Advantages: Advantages:
  
-- Vertical flow reed beds are good for stripping ammonia (the smelly component) from septic tank effluent. They’re also efficient for [BOD](/reed/reed_beds) and suspended solids reductions in tandem with horizontal flow reed beds.+- Vertical flow reed beds are good for stripping ammonia (the smelly component) from septic tank effluent. They’re also efficient for [BOD](https://www.lowimpact.org/categories/reed-beds/further-info/glossary) and suspended solids reductions in tandem with horizontal flow reed beds.
  
 - They can be very effective where space is limited, because they reduce the overall size needed for secondary treatment, which in turn reduces the required size of the follow-up tertiary treatment wetland and final infiltration area. - They can be very effective where space is limited, because they reduce the overall size needed for secondary treatment, which in turn reduces the required size of the follow-up tertiary treatment wetland and final infiltration area.
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 <caption> <caption>
-Common reed (Phragmites australis) is the most common species used in constructed wetlands and reed beds. The dense growth and vigorous roots provide excellent conditions for filtering water. Shown here beside a stormwater pond. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)+_Common reed (Phragmites australis) is the most common species used in constructed wetlands and reed beds. The dense growth and vigorous roots provide excellent conditions for filtering water. Shown here beside a stormwater pond. Source: [FH Wetland Systems](http://www.wetlandsystems.ie/)_
  
 </caption> </caption>
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 Limitations: Limitations:
  
-- A pumped feed is usually needed, which can add to ongoing energy needs and costs. However, where there is a fall on the site a [gravity dosing box, siphon system or effective splitter unit](/reed/reed_beds) may be used instead.+- A pumped feed is usually needed, which can add to ongoing energy needs and costs. However, where there is a fall on the site a [gravity dosing box, siphon system or effective splitter unit](https://www.lowimpact.org/categories/reed-beds/further-info/glossary) may be used instead.
  
 - VF reed beds are best used in conjunction with a horizontal flow bed or other treatment component, and the requirement for an extra system can add to the cost of a project. - VF reed beds are best used in conjunction with a horizontal flow bed or other treatment component, and the requirement for an extra system can add to the cost of a project.
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-## What can I do?+===== What can I do? =====
  
 There are a number of stages to any reed bed project. The more you can do yourself, the lower the overall cost. Reed beds and constructed wetlands generally require planning permission, so if you are good at preparing site drawings, system drawings and good at sourcing design information, this is something you can do yourself. Otherwise you may wish to hand over to a consultancy that specialises in constructed wetland and reed bed design. The excavation, lining, pipework and manhole construction all require input by somebody skilled in that kind of thing. You may hire a mini digger and do it yourself, or you may wish to hire a groundworks contractor, landscaper or sewage treatment system specialist. Planting with the right plants is the final stage (to be carried out before connecting the septic tank!). If you have a boggy field nearby with the right plants, that will be the lowest carbon footprint approach. You may also buy from specialist suppliers if you are stuck. Planting isn't rocket science, but be sure to put the green bit up and the rooty bit down (it happens...). The _Permaculture Guide to Reed Beds_ gives guidance on all of these stages, so if you want to do it yourself, it may be a good book to start with. There are a number of stages to any reed bed project. The more you can do yourself, the lower the overall cost. Reed beds and constructed wetlands generally require planning permission, so if you are good at preparing site drawings, system drawings and good at sourcing design information, this is something you can do yourself. Otherwise you may wish to hand over to a consultancy that specialises in constructed wetland and reed bed design. The excavation, lining, pipework and manhole construction all require input by somebody skilled in that kind of thing. You may hire a mini digger and do it yourself, or you may wish to hire a groundworks contractor, landscaper or sewage treatment system specialist. Planting with the right plants is the final stage (to be carried out before connecting the septic tank!). If you have a boggy field nearby with the right plants, that will be the lowest carbon footprint approach. You may also buy from specialist suppliers if you are stuck. Planting isn't rocket science, but be sure to put the green bit up and the rooty bit down (it happens...). The _Permaculture Guide to Reed Beds_ gives guidance on all of these stages, so if you want to do it yourself, it may be a good book to start with.
  
-See our [further information](/reed/reed_beds) section for summary guides to constructing different types of reed beds, and [here’s](http://lowimpactorg.onyx-sites.io/installing-horizontal-flow-reedbed/) a pictoral guide to installing a horizontal flow reed bed.+See our [further information](https://www.lowimpact.org/categories/reed-beds/further-info) section for summary guides to constructing different types of reed beds, and [here’s](http://lowimpactorg.onyx-sites.io/installing-horizontal-flow-reedbed/) a pictoral guide to installing a horizontal flow reed bed.
  
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 <caption> <caption>
-Excellent demonstration of constructed wetlands for wastewater treatment in Catalunia.+_Excellent demonstration of constructed wetlands for wastewater treatment in Catalunia._
  
 </caption> </caption>
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-### What size should my reed bed be?+==== What size should my reed bed be? ====
  
 Below is a rough guide, based on sizing recommendations from the [EPA](http://www.epa.ie/pubs/advice/water/wastewater/code%20of%20practice%20for%20single%20houses/#.U00LISgww7s) (Ireland) and [GBG-42](https://www.thenbs.com/PublicationIndex/documents/details?Pub=BRE&DocID=250722) (UK). Below is a rough guide, based on sizing recommendations from the [EPA](http://www.epa.ie/pubs/advice/water/wastewater/code%20of%20practice%20for%20single%20houses/#.U00LISgww7s) (Ireland) and [GBG-42](https://www.thenbs.com/PublicationIndex/documents/details?Pub=BRE&DocID=250722) (UK).
  
-| **System type** | **Size per [p.e.](/reed/reed_beds)** | **Minimum size** |+| **System type** | **Size per [p.e.](https://www.lowimpact.org/categories/reed-beds/further-info/glossary)** | **Minimum size** |
 | Horizontal flow gravel reed bed | 5m² | 25m² | | Horizontal flow gravel reed bed | 5m² | 25m² |
 | Vertical flow gravel reed bed | 1-3m² | 15m² | | Vertical flow gravel reed bed | 1-3m² | 15m² |
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 ![](https://www.lowimpact.org/wp-content/uploads/reed-beds-newly-planted-soil-based.jpeg) ![](https://www.lowimpact.org/wp-content/uploads/reed-beds-newly-planted-soil-based.jpeg)
 <caption> <caption>
-Newly planted soil-based constructed wetland system. Source: [FH Wetland Systems](https://wetlandsystems.ie/)+_Newly planted soil-based constructed wetland system. Source: [FH Wetland Systems](https://wetlandsystems.ie/)_
 </caption> </caption>
 </figure> </figure>
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-### Can I use a reed bed for greywater or stormwater?+==== Can I use a reed bed for greywater or stormwater? ====
  
 In many respects using a reed bed for grey water only has certain advantages over treating both black water and grey water together. The system can be smaller because the influent is not as dirty, and has much lower pathogen levels. If you build the wetland sufficiently large, you can reuse the final effluent for watering a polytunnel (note that whatever cleaners, cosmetics or household chemicals you use will end up in your food, so best to use only natural cleaners etc.). In many respects using a reed bed for grey water only has certain advantages over treating both black water and grey water together. The system can be smaller because the influent is not as dirty, and has much lower pathogen levels. If you build the wetland sufficiently large, you can reuse the final effluent for watering a polytunnel (note that whatever cleaners, cosmetics or household chemicals you use will end up in your food, so best to use only natural cleaners etc.).
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 ![](https://www.lowimpact.org/wp-content/uploads/reed-beds-ducks.png) ![](https://www.lowimpact.org/wp-content/uploads/reed-beds-ducks.png)
 <caption> <caption>
-Ducks on a new SUDS wetland pond in Co. Limerick, Ireland. Source: [FH Wetland Systems](https://wetlandsystems.ie/)+_Ducks on a new SUDS wetland pond in Co. Limerick, Ireland. Source: [FH Wetland Systems](https://wetlandsystems.ie/)_
 </caption> </caption>
 </figure> </figure>
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 Constructed wetlands are also excellent for use as SUDS (Sustainable Drainage Systems) to filter runoff from factory yards, roof surfaces and roads. They can be fitted with a variable flow control unit to allow the system to flood during times of heavy rainfall and then draw down slowly in drier weather to balance the flow in nearby streams and to filter the water before reintroducing it into the environment. Constructed wetlands are also excellent for use as SUDS (Sustainable Drainage Systems) to filter runoff from factory yards, roof surfaces and roads. They can be fitted with a variable flow control unit to allow the system to flood during times of heavy rainfall and then draw down slowly in drier weather to balance the flow in nearby streams and to filter the water before reintroducing it into the environment.
 +===== Forum =====
  
-## Further resources+This topic belongs to the section [[gt:water|Water & sewage]]. You can ask questions or add information on the corresponding [Forum section](https://forum.growingthecommons.org/t/water).
  
-## Specialists+===== Further resources ===== 
 + 
 +- [Constructed Wetland Association](https://constructedwetland.co.uk/) 
 +- [EPA (US)](https://www.epa.gov/sites/default/files/2015-10/documents/constructed-wetlands-handbook.pdf) handbook of constructed wetlands 
 +- [Oasis Design](https://oasisdesign.net/) - greywater specialists 
 +- [Reedbeds.co.uk](https://www.reedbeds.co.uk/) - FAQ 
 +- [Sustainable Sanitation Alliance](https://www.susana.org/) 
 + 
 +===== Related topics ===== 
 + 
 +- [[cptt:Compost toilets]] 
 +- [[sewg:sewage|Low-impact sewage treatment]] 
 +- [[pond:Ponds]] 
 +- [[wlur:Waterless urinals]] 
 +- [[sept:Septic_tanks|Septic tanks & drainage fields]] 
 +- [[ntsw:Natural swimming pools]] 
 +- [[wsew:Willow sewage treatment]] 
 + 
 + 
 +===== Specialist curators of this topic =====
  
  
  • reed/reed_beds.1764933010.txt.gz
  • Last modified: 2025/12/05 11:10
  • by Dave Darby