I have just added this to the map of places to fly your drone at Drone Scene:
Land owner permission requirements unknown.
Parking is available at the location (small cost) and there is a café and toilets available. See here: Lliw Reservoirs - Upper and Lower - Swansea for full details.
The property is technically owned by Dŵr Cymru [Welsh Water] and whilst I can't find any specific advice to this site, there is, I believe, a general acceptance to the flying of drones by them so long as one follows all current advice and legislation. Just don't be like the idiot I saw on my visit that flew from the car park!
The originator declared that this location was not inside a Flight Restriction Zone at the time of being flown on 10/01/2020. It remains the responsibility of any pilot to check for any changes before flying at the same location.
