Ffynnon Ddunawd well lies SE of Braich y Saint and consists of a rectuangular chamber cut back into a steep back and placed on the NW corner of a ruined rectangular building. The well chamber is lined with flat-faced stones, reaching a height of 5ft at the back. The sill stone at the front of the well allows a maximum depth of 1ft of water.
Source: RCAHMW Caernarvonshire Inventory, Volume II (No 1419)