 There are now 14 acres ( 5 @.@ 7 ha ) of gardens including St Andrew 's Spring from which the city takes its name . The spring supplies St. Andrew 's Well from which water flows at a rate of 40 imperial gallons ( 180 L ) per second into the moat which holds 4 million imperial gallons ( 18 @,@ 000 @,@ 000 L ) . The water emerging from the spring originates from the cave system of the Mendip Hills including Thrupe Lane Swallet . The Well House was built in 1451 , for Bishop Beckington to provide water to the citizens of Wells in the market place . The small stone building with a slate roof has a central hole in the stone floor giving access to the well itself . The gardens are listed , Grade II * , on the Register of Historic Parks and Gardens of special historic interest in England . 
