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

• Better use of the water (most of the evaporation will be through the plant's leaves), makes the method specially useful in arid climates. It is this aspect Gus Nilsson makes use of.
• More efficient use of the area (e.g. in greenhouses or other glazed areas).
• In a greenhouse where the wall is used as a greywater purification device, it also works as a heat exchanger and -buffer
• Purification of the percolating water, if you use greywater as irrigation.
• If the passage through the wall is long enough (25 - 30 sq.m/person) the purification will probably be so efficient that the water can be re-used, at least for greywater purpuses.
• In warm climates, the wall can be used as building material on the sunny side. This will cool the building.

The basic design is a wall of hollow stones of concrete with compartments. 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. 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, releasing the nutrients in the percolating organic material. In order to let the water trickle as long way as possible, horizontal plastic sheets are put into the bed between the stones.

Under the wall, you put some type of container to collect the water, so the purified wayer can be collected and returned to the top of the wall or used.

The though of vertical gardening is not new. For example, it was used in the hanging garedens of Babylon. Vertical gardening is also used in hydroponic containers.
Gus Nilsson, in Gabarone, Botswana, has also used the metod for a long time. However, nobody seems to have used the method for water purification, but instead, water and nourishment are supplied directly for the needs of the plants. I proposed this combined use in a study for Kimberly minicipality in South Afrika 1998. Of course, to be used for water purification, the water should be as unpolluted as possible, which can be attained with the use of source-separating toilets.

• 1998 I visit Gus Nilsson in Gabarone, Botswana and become inspired by his type of vertical growing.
• 1998 - 2001 Different stone types are invented and studied.
• 2000 I propose the construction of a folkewall at the Aniara-exhibition at the Swedish Museum of Natural History. After changes and budget cutting downs, the end result is not very encouraging.
• 2000 I propose the installation of a folkewall at Ekotopia, Aneby
• 2001 It is decides that a folkewall shall be put up at The Gardening Exhibition i Älvsjö, 11 - 14 april 2002 with the Swedish Pernaculture Association.
• 2001 dec Contact with Nigel Wells, Virbela
• 2002 jan. Contacted by Olle Skoglund, TaForm regarding the casting of the stones.

• 2002 4 feb. The First models are made, pictures by Olle Skoglund

Here are some pictures of the model:

The wall is erected of the blocks. Under the wall is a container to collect the water that circulates through the wall.	The stones are constructer like an inverted T in order to fit into each other. They are put halfway up on each other. Under the right, lowest is a line of bricks.
To show the function, the wall is connected with a washing-up sink.	The water is pumped up to the top of the wall and trickle down through the inert stones. (You can see the hole on the picture) to the collection container below.

Since the casting was problematic, a new casting method was designed. It consitsts of a 3+1 step casting.

The outer moulds

The inner moulds and the three casting procedures.

The final step, after the first part has solidified.