Tanks - Fosse For the pre-treatment of effluent the minimum tank size is 3000 litres which covers up to 3 bedrooms after that you need to add 1000 litres for every subsequent bedroom.. 1. Polyurethane tank: 2. Eparco compact system: Filters - Filtre The filter treats the water that has been through the tank and disperses it into the ground or into a ditch. There are various different types of depending on the type of land. 1. Gravel drainage - Epandage EP: These are used when there is plenty of land with good permeability 4. Eparco compact system: For small spaces 2. Filter free draining - Filtre sable non draine This is for land with good permeability but less space. 3. Sand filter - Filtre sable draine : This is for impermeable land or land near a water source or well.   5. Tertre: The filter is placed in a bank above ground and only used in cases where the land is too wet for drainage: Supplementary items: Pump - Poste de relèvement : Used when the slope of the land means the system can not be gravity fed. Grease Trap - Bac dégraisseur : These are needed when the tank is further than 8-10m from the house. It separates the grease from the waste before it enters the tank Rainwater collection tank To store rainwater for use in house or garden.