At an unknown date a section of the stream was lined with slate and a wood-framed dunny or latrine was built over it to provide toilet facilities with constant running water.
Originally this building was separate from the engine shed, but the space between the two has now been roofed to provide a toilet block.
This building is now the headquarters of the railway's passenger carriage construction programme, as well as being a base for the overhauling of freight and engineering vehicles.
The original railway did not have a passenger station at Maespoeth, although most up-trains halted there to take water from a pipe overhanging the track, fed from a slate water tank inside the engine shed, supplied via a cast-iron pipe from a mountain stream several hundred yards away.
The heritage railway has built a platform at Maespoeth and this currently serves as the southern terminus of the partially restored line.
This last spur of the old tramway is still occasionally used as a facility for transferring engines and rolling stock to flatbed lorries for road transportation.