Easy to maintain and more economical than a septic tank, phytodepuration is an autonomous and ecological individual wastewater treatment solution.

Particularly suitable for rural areas not connected to the sewer, this treatment process is simple to install, inexpensive and even has the advantage of being aesthetic.

Ideal for a land intended for a Tiny House, self-built or not 🙂

In this article, we explain how phytoepuration works and how to make one yourself.


Set up a phytodepuration system
Source: Pinterest

It is a natural process by plants to filter and clean up wastewater.

Totally ecological and odourless, phytodepuration consists of purifying wastewater thanks to the bacteria present in the roots of purifying plants (bamboos, reeds, cattails and sedges are the most commonly used).


How does phytodepuration work?
Source: Pinterest

Nature takes care of everything. It is the bacteria in the roots of plants that will purify the water.

These bacteria are called aerobic, which means that they need oxygen and do not give off bad odours. They will thus transform organic matter into mineral matter, which can then be assimilated by plants.

In exchange, aquatic plants will provide the oxygen needed for bacteria through their roots.

These plants adapt to all types of soil and to different times of the year. They can withstand both wet periods, i.e. when the house is occupied, and dry periods, when the house is empty.

Another advantage of this wastewater treatment system is that there is no smell.

Why? Because, unlike a septic tank which follows the same principle as fermentation in a confined environment without oxygen and where the incomplete decomposition generates gases and sludge, the phyto-treatment is based on the same principle as composting. Thus, in contact with the air, the degradation is complete and produces organic matter (humus and water vapor).

It should be noted, however, that at the beginning of the installation of the system by planted filters, the sand will not be invaded by the reeds and may give off slight odors. But these will disappear as soon as the reeds have spread over the entire surface of the filter!

Another question mark concerning the functioning of a plant nursery: frost in winter. Here again, no fear! The plants installed are naturally present in the water bodies and therefore frost resistant. In addition, the constant supply of water to the plant purification system limits the formation of frost. Finally, if there is frost, it will only be on the surface because underneath the bacteria will continue to work, to create energy and therefore heat.


The 3 steps of a phytodepuration

1. Pre-treatment

In the basin, pebbles and reed roots will leave macro-particles on the surface of the water. The other elements will be turned into compost.

2. Processing of chemical compounds

The purification plants installed in the basin will suck out nitrates, phosphates and metals. During this2nd stage, the pollutants, which are mainly household, will be broken down.

3. Biological water treatment

Composts stored at plant roots will be “eaten” by bacteria and will be transformed into mineral materials that plants will feed on.


Maintenance of a phytodepuration system
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Except for “gardening” maintenance such as mowing, weeding, and cutting the reeds once or twice a year, there is nothing to do!

Simply plan every 10 to 15 years to remove the surface layer of compost from the rake, which can be used as a fertilizer for the rest of the garden.

This low maintenance requirement is one of the reasons why the planted filter water treatment system is more economical than a septic tank.

Family of 4 to 5 people
Family of 4 to 5 people
Installation fee:About 6000 eurosAbout 4500 euros
Interview:Paying, maximum every 4 years by a professionalFree, gardening once or twice a year.
Installation time:Maximum 20 years if well maintainedAbout 25 years

Think also to inquire about the eco-loan at zero rate and the other aids which you could have by installing a phyto-purification. Information on Ministry of Ecological and Solidarity Transition .


Installing a plant purification system yourself
Source: Pinterest

The installation of a planted filter sanitation system can of course be done by a professional, but the public services also allow you to install it yourself, following these guidelines:

“The commune (or, in some cases, the commune or agglomeration community) examines its design by studying the file provided by the owner, supplemented by a site visit, if necessary. It also verifies its execution on the basis of the preliminary examination of the design of the installation and during a site visit carried out before backfilling. This examination is carried out by the Public Service for Non-Collective Sanitation (SPANC).

Non-compliant installations must be brought into compliance within 4 years in the event of a health hazard or proven environmental risk. This period is reduced to 1 year in case of sale of the building or house.

The owner must regularly maintain his installation (maintenance, emptying).

The SPANC checks the proper functioning and maintenance of the installation at most every 10 years.” Consult here the regulations on wastewater treatment.

In installation area, plan about 24m2 of plant-clearing ponds for a family of 4/5 people. This natural sanitation system will be built according to the principles of vertical and horizontal filtering:

Vertical filtering by plants :

The wastewater will be conveyed to the first basin where only reeds are planted. Indeed, these plants have the specificity to produce a lot of oxygen and thus allow the development of a maximum of bacteria.

Moreover, the movement of these light plants will prevent the waste transformed into soil from clogging the gravel filter.
Then, in the last basin, other plants are used for a more precise filtration.

Horizontal filtering through the arrangement of the basins:

At the beginning of the conveyance system, the wastewater is filtered through a grate that will allow to recover the biggest waste.

In each basin, increasingly fine gravel and sand are placed to filter the water horizontally. In addition, a drain is also installed to evacuate water.

Thefirst pool is located higher than the second so that the water drains naturally. Thus, your ground must have a difference in level of more than 1 meter for the installation of the phyto-purification. If this is not the case, it will be necessary to install a lift pump to transport the water from one pool to another.

For more technical details on the installation of a phytodepuration system, we advise you to consult the magazine La Maison Écologique N°115 .

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