The invention relates to a tank (100) provided with at least one effluent-filling opening and at least two effluent-emptying openings, a bucket capable of tilting between a filling position, in which it can be filled with an incoming effluent through said at least one filling opening, and a discharge position, in which it can discharge the contents thereof through one or more of said emptying openings. According to the invention, the tank (100) includes means for modifying the position of the bucket (200, 200′) so as to change the direction thereof or to enable the replacement thereof with another bucket of a different type.It is thus possible to modify the effluent outlet direction by a simple change in the bucket position. It is also possible to replace a bucket with a bucket of a different type.In this way greater versatility of the adaptation to the connection of the tank on the installation site is afforded.