To ensure that the water runs to the drain, the wetroom floor has to be designed to form a subtle, even gradient. In older homes this is sometimes problematic and where it’s not possible to get the slope right, a concealed tray is a good alternative.
If draining towards a central gulley drain, large-format tiles need to be cut diagonally into the depression angle of the underlay; otherwise smaller mosaic tiles can be used. Do make sure that the drain isn’t positioned directly beneath the showerer’s feet. In smaller spaces, you may find a corner drain, with the floor sloping towards it, an easier option. Channel drains,positioned at the entrance to the shower are a popular option, and create a larger drainage area.
Draining the waste water can sometimes be a problem, as the waste pipe needs to run to an external wall or soil stack. If your wetroom is at the opposite side of the house to the drains, then you may need to install a pumped drain, with a sensor to automatically start when water is present. This may also be necessary if there is insufficient space under the floor to create a fall for the waste pipe.