Elsewhere, remnants of the medieval water supply system devised by the friars can still be seen today. Constructed in 1290, the system carried water from Conduit Head (remnants of which survive near Hill Lane, Shirley) some 1.7 kilometres to the site of the friary inside the town walls. The friars granted use of the water to the town in 1310 and passed on ownership of the water supply system itself in 1420. Further remains can be observed at Conduit House on Commercial Road.

In what year was the friars' water supply system built in Southampton?