NOVELTY - Treatment of effluents of communities in which a wastewater system is used for collecting rain or infiltration water. Flow rate of the effluents varies between a dry weather period and a rainy weather period. A purification plant (1) is used for adapting the effluent flow rate in the dry weather. A filter bed (12) with grown plants is arranged upstream of a treatment plant and is used for stocking a polluted hydric excess without fermenting. The water stored in the filter bed is evacuated over one week or more.    USE - The invention deals with treatment of effluents of communities equipped with wastewater system.    ADVANTAGE - Cost effective treatment of effluents of communities. Quality treatment of effluents of communities is achieved even in the strong rain.    DETAILED DESCRIPTION - Treatment of effluents of communities in which a wastewater system is used for collecting rain or infiltration water. Flow rate of the effluents varies between a dry weather period and a rainy weather period. A purification plant is used for adapting the effluent flow rate in the dry weather. A filter bed with grown plants is arranged upstream of a treatment plant and is used for stocking a polluted hydric excess without fermenting. The water stored in the filter bed is evacuated over one week or more. The period for reducing stocking of the stored water in the filter bed is followed from one period of rest of a week, to avoid stratification of heterogeneous layers of mud. The water storage is carried out for two weeks for prolonged immersion of the grown plants. A valve (H) directs the flow of effluent towards the purification plant when the storage capacity of the filter bed is reached.    An INDEPENDENT CLAIM is included for an installation for treating effluents of communities.    DESCRIPTION OF DRAWING(S) - The drawing shows an installation for treating effluents of communities equipped with a wastewater system:    Purification plant; (1)    Storm overflow channel; (8)    Filter bed; (12)    Pumping station; (15)    Valve. (H)