A water trap (1) improved with respect to handling and operational safety includes: two semipermeable membranes (2) and at least one tank (7), wherein the membranes have a water penetration pressure greater than 750 hPa and are made of the same or different PTFE laminates. The gas flow is divided in a ratio between 10:90 and 25:75 into the flush-/purge branch and analysis branch to the sensors (12) and a path parallel to the sensors (12), respectively, with the aid of the membranes and downstream filter elements and via the material and configuration.