The 'folkewall' - Vertical growing

Greywater purification and vertical growing, previously called 'the living wall'

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A common principle in permaculture is that every unit should perform serveral functions.

By growing plants in a porpos wall, you get both an efficient space use by vertical plant growing and purificaltion of the percolating water, which may be greywater.

The hollow parts of the stones are filled with inert material, like gravel, LECA-pebbles, perlite or vermiculite. The stones are placed so the water will percolate in zig-zag through the wall. Bacterials in the porous material break down organic pullutants. The water trickling down through the wall will nourish the plants at the same time as it will be purified The plant roots will grow into the inert material and extract nutrients from the water. Over the pepples, a film of bacterials will grow. After comsuming the organic material they release the nutrients in the percolating water. The plants will take up the nutrients and subsidize the bacteria with sugar from their photosynthesis.

By this, you get both vertical growing and greywater purification.

Therefore, the efficiency of the purification is dependent on the amount of solar radiation reaching the plants in the wall.

  • Better utilisation of the irrigation water Most of the evaporation goes through the leaves of the plants, which is good in a dry climate. It is this aspect that Gus Nilsson in Botswana uses.

  • Better utilisation of the growing area (for example in greenhouses or other areas under glass, or in urban farming in a frost-free climate)

  • Food production The plants can be of ornamental or any domestic use.
    In warm climates, the food production can go on all the year around, simultaneous with the water purification.
    With the folkewall method, food production is combined with water purification.

  • Heat exchanger and temperature buffer in a greenhouse where the wall is combined with greywater purification.

  • Purification of the percolating greywater.

  • Water re-use. With a long enough passage through the living wall, the water is sufficiently clean for re-use as utility water.

  • Cooling. In hot climates, the wall can be used as wall material on the sunny side. This will cool the building.


The basic design is a hollow wall with poaches for plant growing.

The innner part of the wall is inert and porous, a filling of gravel, LECA-pellets or course sand. Through this media, the water to be purified percolates, just like in hydroponic growing.
The roots of the plants grow into the porous material and use the nutrients in the water. With the bacteria growing on the medium, this will become a very effective system for water purification.

To make the water run as long way as possible, in a zigzag pattern through the substrate, horizontal plastic sheets are put in, or the concrete is formed to let the water flow in a zigzag pattern.

In the bottom of the wall, the water is collected in a tank to be used in the household or pumped to the top of the wall again.





The thought of vertical growing is not a new one. The hanging gardens of babylon are well known. Vertical growing in hydroponic containers are also used.
Gus Nilsson in Gabarone, Botswana has, among else, used the vertical growing method for a length of time.
None of these, however, has used the method for greywater purification, but supplied water with a content of nutrients directly for the needs of the plants.
In a study for Kimberly municipality in South Afrika 1998, I proposed this way of using the grey water in combination with urban gardening. To be possible to use as a part of normal settlement, source separating toilets are needed to produce as clean greywater as possible.

The wall is designed in three types

Made of standardized concrete stones.

More info about this type.

Soon, you can ownload an instruction for making moulds for stone-casting.

Made in a sandwich pattern of concrete

More info about this type.

Made from old tires and plastic sheets

More info about this type.

Download a description of how to build a folkewall from used tires and plastic bags!

Extra! The first five who send me pictures on their own folkewall projects will be refunded!
Download a free poster! (0.6 MB)

Do you want information about the progress of these projects? Add your e-mail address to the mailing list below!

More about greywater design systems at Oasis design

Greywater purification methods for cold, humid climates


From standard stones

Sandwich type

From tires

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