Wastewater Treatment Plants for Secondary Homes

According to the INSEE, a secondary home or secondary residence is a dwelling used for vacations, leisure or weekends.

The regulations of the non-collective sewage treatment in France distinguish two types of use:

1. Permanent use: daily presence with temporary absences.
2. Intermittent use: occasional presence with long periods of absence.

The French regulation assimilates the principal residence to a permanent use of the dwelling and the secondary residence to an intermittent use. This approach is not perfect because the use of a dwelling is not fixed, for example, some people may spend more time in their second home than in their main residence.

The French regulation does not allow the use of the micro-station in secondary homes because of the:

• Variation in terms of hydraulic and organic load linked to intermittent use of the dwelling. A long period of absence leads to the degradation of the bacterial flora due to a lack of “food.” When you return, the system will not function normally until the bacterial flora regenerates.
• Need for a permanent power supply. In the case of a prolonged power cut, the absence of oxygenation leads to the reduction or disappearance of the bacterial flora. This is not a problem for main houses where you will restore the power quickly. However, it will be prohibitive for secondary homes where the owner will not be there for weeks or even months. When you return, the system will not function normally. To promote the regeneration of the bacterial flora, it will be necessary to clean and restart the installation.

Therefore, a small wastewater treatment plants cannot be connected to a secondary home. On the other hand, the compact filter works for both.

The compact filter, composed of a septic tank and a filter bed, is the ideal solution for secondary homes. This system is almost as compact as the micro-station and is part of the approved systems among the small wastewater treatment plants.

The operation of the compact filter is based on a combined biological and physical treatment mode: the biological treatment, common to all sewage treatment systems, requires the presence of a bacterial flora, sensitive to intermittent use. The filter support, for example the coconut fibre used by Tricel, allows the physical treatment of the effluents by filtration, whatever the use of the housing.

In the case of intermittent use, the physical treatment ensures minimum effluent treatment.

The compact filter and the micro-station require a minimum surface area that is smaller than a septic tank system with percolation area. The compact filter operates without electricity.

Other important advantages of the compact filter:

• Compact: Compact: much smaller hold on the ground than a septic tank with a percolation area
• Passive: does not consume energy to operate
• Eligible to the “éco-prêt à taux zéro”