I can't find any info about the actual adit online, so I thought I'd do a mini trip report.
I was up having a look at the water-wheel back in August, noting the two flooded shafts surrounded by fencing, and the flooded pumping shaft. There is suprisingly little spoil at the site. I noticed some more spoil a bit further up from the wheel. Investigation led to a semi-hidden trench leading to a wet looking adit. Lack of torch meant leaving for another day.
Which was yesterday. Entering the adit, your are immediately met with boll*ck deep water which continues via a couple of minor exploratory cross cuts to a junction with a passage to the left. Onwards leads to a loose terminal 'chamber', where the water is now down to foot level, making it safe to tentatively take the phone out for a photo. Back at the junction, a few metres into the passage, apparent in the water, is a flooded winze, depth unknown with the remains of a wooden platform around the rim. I didn't see any signs of copper, but there were nice flow deposits of black manganese, white hydrozincite, and nice yellow, iron stained calcite. Total length - approx 100m.
This adit presumably is unconnected with the other three shafts as the water level at the winze is perched at a few metres above the flooded surface shafts. An article on AN suggests that Cwm Cipwrth was a pumping and access site for the nearby Gilfach. I disagree. I think it's just a small share puffing enterprise with just enough workings to make it look like a going concern to investors - a familiar story.
It would be interesting if a camera could be put down the flooded shafts and winzes.