The Mosshouse Wood Reservoir is an impoundment of over 5 million gallons capacity and the area around it is a wonderful example of a small Victorian water supply reservoir, creating a tranquil and attractive landscape. It was constructed at the end of the 19th Century to provide a water supply for the expanding town of Neath. Stored water was discharged by pipeline to the filter beds adjacent to the Fishpond.
Below the reservoir, the Llantwit Brook has cut a deep valley and a watercourse was dug early in the 18th Century along the Eastern edge. A drainage leat following the contours also connects the lower spillway with Fishpond and the Guinea Pond. The reservoir was released as surplus to requirements by the Water Authority in 1982.
Mosshouse Wood covers the eastern flank of the Gnoll Estate Country Park. Much of the wood consists of conifer plantations dating from the 1950's interspersed with small areas of beech.