The invention relates to a toilet system (1) for installation in a vehicle, wherein the toilet system comprises the following components indicated: namely a base (2) which is to be fixed to the vehicle and has a top wall portion, also a toilet bowl (3) which is borne by the top wall portion of the base and has a top peripheral portion preferably bearing a toilet-seat ring (6), further a sewage-retention tank (15) which, in the use position, is arranged, at least in part, beneath the top wall portion, and additionally a guiding, retaining and coupling device which is configured such that the user—preferably from the outside of the vehicle—can pull the correspondingly formed sewage-retention tank out of its use position, in which it can be connected in a liquid-tight manner to the outflow of the toilet bowl (3), remove it from the vehicle and then replace it in said use position, wherein the toilet system (1) is configured such that, even after the base has been fixed to the vehicle, it is possible to make a selection between different intended positions in which the user can sit on the toilet bowl (3) of the toilet system (1), wherein the toilet bowl (3) is fixed to the base (2) in a predetermined position relative to the base, and at least the top peripheral portion of the toilet bowl (3) is essentially round and the toilet-seat ring (6) can be secured on the toilet bowl (3) in different positions, in which it has been rotated at different angles in relation to the vertical axis of the top peripheral portion.