 The original aqueduct is 4.5 miles (7.2 km) long and ends at the siphon chamber in Cranston, where it splits into a series of smaller and smaller conduits that supply the water delivery system.The other 78- and aqueduct is 9.5 miles (15.3 km) long and was built in the 1970s to supplement the original aqueduct.75% of distribution is by gravity and 25% by pumping.