Follow along
A Potable History of Y Fach
Beneath the limestone bulk of the Great Orme in Llandudno lies a little-known Victorian relic: Y Fach, a disused underground reservoir whose brick vaults once held nearly a million gallons of water. Its vast, vaulted interior, crafted from 248 red brick arches, spans around a third of an acre with a roof height of 19ft. Its existence is tied to the rapid growth of Llandudno during the 19th century, when the small coastal settlement transformed into one of Britain’s most fashionable seaside resorts. With thousands of visitors arriving by train and an expanding local population, demand for clean, reliable water became urgent.
Original surface springs and wells were proving inadequate
By the 1870s, Llandudno’s original surface springs and wells were proving inadequate. Local authorities commissioned engineers to design a modern water storage system that could both collect upland water and regulate supply to the town.
The solution was ambitious: a subterranean reservoir, dug directly into the Orme’s solid limestone and lined with brick vaulting. This not only provided security and cleanliness, but also meant the structure could be hidden away, preserving the scenic beauty of the headland.
Known locally as Y Fach—“the little one”—the reservoir was completed in the late 19th century. Despite its modest name, it was an impressive feat of engineering. Workers excavated a large chamber, reinforced with massive red-brick arches, creating a cathedral-like interior.
Rainwater was gathered from catchments on the Orme and channelled inside, where the cool underground conditions kept the supply fresh. From here, water was piped into the growing town below.
Despite its modest name, it was an impressive feat of engineering
Y Fach survives as a unique piece of industrial heritage
For decades, Y Fach quietly did its job, largely invisible to both residents and visitors. Its presence was known mainly to the water engineers who inspected and maintained it.
The reservoir formed part of a wider network of Victorian public works that underpinned Llandudno’s reputation as a safe, modern, and healthy holiday resort. Without such infrastructure, the town could not have sustained its boom years.
By the mid-20th century, however, water demand had again outstripped supply. Advances in engineering and public health led to the construction of larger, more efficient reservoirs in the Conwy Valley and surrounding uplands. Y Fach, though still functional, was gradually made redundant. It was drained, sealed, and left dormant beneath the Orme.
In its abandonment, Y Fach became something of a hidden legend. Few locals had ever been inside, and the atmospheric interior—dark, dripping, and cavernous—fired the imagination. Some likened it to a crypt or a vault, others to a subterranean chapel. Its very obscurity gave it an aura of mystery, tied up with the Great Orme’s broader history of caves, mines, and folklore.
Today, Y Fach survives as a unique piece of industrial heritage: an underground time capsule of Victorian ambition and engineering skill. Though no longer part of the water supply, it stands as a reminder of the unseen infrastructure that enabled Llandudno’s rise, and of the human capacity to shape even the depths of the rock for civic needs. Plans to bring it back into public life—as a place of history, storytelling, and imagination—promise to reconnect the reservoir with the community it once quietly served.
Our first exploration of the drained reservoir. We picked up some curious sounds on the audio...
What's down there?
Find out more
Get in touch
Please reach out if you want to collaborate with us, or simply have a chat.
© 2026 Llandudno Vaults
Web Design: ash-jones.co.uk
Get in touch
Please reach out if you want to collaborate with us, or simply have a chat.
© 2026 Llandudno Vaults
Web Design: ash-jones.co.uk