You can check the capacity of the water deposit under de Included features:
The dirty water from the kitchen sink + shower run together into the grey water deposit under the camper. After using one freshwater tank, it is recommended to empty the grey water deposit, as this can release strong odors and cause overflowing into the sink and shower if not emptied regularly. Usually, the grey water tank is smaller than the freshwater tank, so it will get full before the fresh one gets empty. To dispose of the grey water properly, ensure the camper is parked over a proper water discharge station*. Then open the grey water deposit by accessing the red faucet located under the right side of the camper.
* Water discharge stations may be found in several locations such as camping sites and all around Europe, you will find water facilities that allow you to refill the water deposit in your camper. Camping grounds, service areas, or fuel stations are normal places where this is possible.