1. This culvert is one of the few surviving elements of the Castell Malgwyn Tinplate Works (NPRN: 404326). It is 26m in length and runs underground from what orginally would have been the retaining wall for the canal (NPRN: 404580) which conveyed water to the works, out to the River Teifi. It currently feeds water from the River Morgennau into the Teifi.

The culvert comprises of two chambers, which are curved in plan and constructed of a brick vault on stone slab side walls. The intake and outtake consist of a double arched portal, one for each chamber, most clearly seen on the outtake side. This has stepped cutwaters extending 1m in front of the face of the portal and is constructed of coursed stone slabs, with segmental arches, 1.5m wide, the soldiers of which are formed of edged slabs.

There are two possible functions for this structure, the most likely is that it served as an outflow for the canal water and the other is that it served as a leat to convey water to one or more of the water wheels which powered the rolling mills of the works. There is a change in level along the line of the culvert, which is apparent when listening to the sound of water flow and indicates a waterfall at some point along its course. The most likely explanation for this is that due to the tidal nature of the Teifi, it would have been essential to have a difference in level between the water feeding the complex and that of the outflow area, otherwise when the tide rose, water would have flowed back into the works.

Louise Barker, RCAHMW, 12th July 1006