"This building which was photographed around 1970 and was a pumping station that was part of the Charlottetown Water Works located near the corner of Cumberland and King Streets. The site is now the location of an expanded power plant for Maritime Electric. A new pumping station was constructed to replace this building at the bottom of Cumberland St."
Photos and quote cf. Vintage Charlottetown on Facebook https://www.facebook.com/VintageCharlottetown/photos/pb.355081987910947.-2207520000.1395315863./593317240754086/?type=3&theater
Above: note the current Maritime Electric building on the far left.