After the war, the building was returned to its owners and the Hydro reopened. Many things had been changed by the war and there was little future for such an establishment at this time, so the Craiglockhart Hydropathic went into voluntary liquidation in 1920.
It was sold to the trustees of the Society of the Sacred Heart, an enclosed religious order, to be used as a convent and training college for Catholic teachers. Also, at this time Craiglockhart became part of Edinburgh, as the Colinton Parish was subsumed into the city. The main building was added to over the years with a Chapel opened in 1933 and extended in 1963, and a new wing on the other side of the building built in 1957. In 1965 a six-storey hall of residence was added along with a new lecture block, hall and gymnasium and the whole was renamed Craiglockhart College of Education, which it remained for the next 30 years.
The most recent chapter in the history of the building and its environs began in 1986 when the College was bought by Napier College of Commerce and Technology, now Edinburgh Napier University.