The building of the reservoirs, and the improved supply of clean water that came with them, was life-changing for the people of Cardiff.
The origin of Lisvane & Llanishen Reservoirs may be traced back to the 19th Century. Cardiff underwent rapid growth as a major coal-exporting port with the opening of the West Bute Dock in 1839 and the construction of the Taff Vale Railway that supplied the dock.
Trade and the population increased but the town’s utility services did not keep up. Insanitary conditions led to major outbreaks of diseases such as typhoid and cholera. When the link between these diseases and contaminated drinking water was finally understood, Cardiff Corporation took steps to provide a proper and adequate water supply for the town.
An Act of Parliament in 1860 proposed the creation of the Lisvane Reservoir to store water from the Llanishen, Nant Mawr, Nant Draw, Nant Felin and Nant Dulas streams.
Construction of a new storage reservoir at Lisvane began in 1864 and it was completed a year later in 1865.
Filter beds were also constructed on what would later become Llanishen Reservoir.
The population of Cardiff continued to grow and, by the end of the 1870s, water was again getting in short supply. Cardiff Corporation came up with a radical solution; to build a number of reservoirs in the Taf Fawr valley of the Brecon Beacons and constructing a thirty-two-mile pipeline back to Cardiff where the water could be stored in a new holding reservoir adjacent to Lisvane Reservoir.
Under the auspices of Borough Engineer John Avery Brandon Williams, work started on Llanishen Reservoir early in 1884 and was finished in 1886. It was created on largely flat land with a surrounding bank of earth with a clay core and hand-cut stone on the inner surface.
Following the completion of Cantref Reservoir in 1892, water began to be piped down to Llanishen via the new infrastructure. When the Taf Fawr Scheme was completed, the pipeline could deliver up to 12 million gallons a day to Llanishen Reservoir which itself could hold 317 million gallons of water.
The hand-cut stone lining and much of the original valve gear, pipework and fish traps may still be seen.
Today, Llanishen Reservoir is designated as a listed building, recognising the innovative engineering that went into its construction.
The screening chamber and lifting gantry next to Llanishen Reservoir were installed later. The screening chamber filtered water drawn from the reservoir before it entered the cast iron main supply pipework. The lifting gantry was used for maintenance of the screening chamber and screens.
In the mid 1960s, Cardiff Corporation built a new reservoir at Llandegfedd, just outside Pontypool (also a Welsh Water Visitor Attraction) which became the primary water supply for Cardiff. The filter beds in Allensbank Road were decommissioned in 1968 and water from Llanishen was pumped up to the Wenallt Reservoir in Rhiwbina, from where it continued to be used as an emergency backup supply, only capable of providing three million gallons per day.
In the mid 1970’s it was decided that Llanishen Reservoir had come to the end of its useful life. It was not drained but ceased to receive water from the Taf Fawr pipeline and was just kept topped up by rainwater.
Llanishen Reservoir started being used as a venue for sailing in 1967. The landing jetty was constructed in 1968 and Cardiff Education Authority set up a sailing centre in 1968. The reservoir continued to be used as a sailing centre and a fly-fishing club until 2004 when the two reservoirs were acquired by Western Power Distribution
In 2004, public access ended. A planning application was made to drain Llanishen and build over 300 houses. The reservoir was subsequently drained but the Reservoir Action Group was at the forefront of opposition to the redevelopment of the reservoir.
After numerous public inquiries, planning consent was finally refused in 2013 due to the harm the scheme would have caused to the structure of the reservoir and its setting. Western Power Distribution sold the reservoirs in 2013 to Celsa to secure a water supply to the Allied Steel and Wire works in Cardiff Bay (Cardiff Corporation started supplying water from Lisvane Reservoir to the Castle Steel Works, Tremorfa, in 1936). In 2016, Celsa granted a 999-year lease for the site to Welsh Water.
In 2017, Welsh Water undertook extensive repairs to the stone pitching, valve tower and other infrastructure and began refilling Llanishen Reservoir. The company’s Dam Safety Team undertook further works in 2020 in preparation for the change of use to a visitor attraction.
Also in 2020, an ecological survey found an astonishing 24 species of waxcap on site. For more information about waxcaps at Lisvane & Llanishen Reservoirs, check out our nature pages.
Between 2021 and 2023 with support from Welsh Government and National Heritage Lottery Scheme, Welsh Water continued to make improvements across the Lisvane & Llanishen estate to support the environment and biodiversity. Find out more here.
And so, after significant investment and development by Welsh Water, Lisvane & Llanishen Reservoirs is now a hub for health, wellbeing and recreation, an ‘island’ of nature in the Cardiff suburbs, reconnecting you with the outdoors and water.