Water and power

Before the implementation of a centralized public water supply, Gwalchmai residents traditionally relied on private wells and springs. A specific “well” is mentioned in recent planning documents as being located near Bryn Cwr in Gwalchmai.

Location of springs 1913

The reliance on these traditional sources was replaced starting in 1951 with the completion of the Llyn Cefni reservoir, which provided a sanitized, piped water supply to central Anglesey, including Gwalchmai.

The reservoir was created by damming the Afon Cefni.Construction began in the late 1940s and reached completion in 1951.It was designed to capture water from key tributaries, including the Afon Frogwy and the Afon Erddreiniog.

Water from Llyn Cefni is pumped to a service reservoir near Bryn Clegir farm to provide water to the village.

With the centralized system, water management evolved to include chemical safety. By the 1960s, the Llyn Cefni treatment works implemented sophisticated filtration and chlorination protocols to ensure the water met modern health standards

In terms of modern utilities, the village is served by the Gwalchmai Sewage Treatment Works, in Gwalchmai Uchaf, which manages effluent from the settlement and the nearby Mona Business Park. There is also a sewerage pumping station near “pant”

Electrical power is supplied to Gwalchmai through a tiered transmission and distribution network managed by the National Grid and SP Manweb (the Distribution Network Operator for North Wales).

The supply process involves the following stages:

  • High-Voltage Transmission: Electricity is initially carried across Anglesey via the National Grid’s 400kV transmission system, which includes a double circuit line running between the Wylfa Power Station and the Pentir substation.
  • Regional Distribution: SP Manweb takes power from the National Grid and distributes it through a regional network. In the western part of Anglesey, 132kV overhead lines carry power to local grid substations.
  • Voltage Transformation at Caergeiliog: A primary point of supply for the Gwalchmai area is the Caergeiliog grid substation. At this facility, the 132kV voltage is lowered to 33kV using large transformers.
  • Local Supply to Gwalchmai: Once reduced to 33kV, the electricity is distributed to local communities through a network of overhead lines and underground cables. Maps of the island’s electrical infrastructure show that Gwalchmai is situated along corridors for both 132kV and 33kV distribution lines.

The presence of this infrastructure is locally visible, as evidenced by the overhead power lines located near the Gwalchmai showground. To ensure the continued reliability of this supply and to support future demand, energy providers have invested in reinforcing the nearby Caergeiliog substation and its associated 132kV circuits