Waterwheel housing, Gilfach Ddu, Llanberis

Waterwheel housing, Gilfach Ddu, Llanberis

Through the gateway here you can see the rear yard of the former Dinorwig quarry workshops, now home to the National Slate Museum.  

The tall rectangular stone structure houses the giant waterwheel which powered machines in the workshops. 

The wheel is more than 15 metres (50ft) in diameter. Its components were cast in Caernarfon in 1870 by the De Winton foundry, whose buildings still stand in the town. It is the largest waterwheel in Great Britain, second only in the UK to the Laxey Wheel on the Isle of Man. 

It is fed by water from the tank at the top of the structure which houses the wheel. The water tank was, and still is, supplied from Ceunant Mawr, near the Llanberis Path up Snowdon – on the far side of the valley. The water is brought here in a cast iron pipe. There’s no shortage of rainwater on the mountains to replenish the tank!

The giant wheel operated until 1925, when it was replaced by a Pelton wheel, a more efficient type of waterwheel. 

Museum visitors can walk up the staircase to see the waterwheel, which still turns today. Follow the link below for visiting information.

To the left as you look through the gateway is a row of quarrymen’s houses named Fron Haul. They were originally in Tanygrisiau, near Blaenau Ffestiniog. In 1999 they were carefully dismantled and re-erected here. Each cottage is furnished to show how quarry families lived in different periods of history. 

Postcode: LL55 4TY    View Location Map

National Slate Museum website