Adam Clarke Bible Commentary

Ye gathered together the waters "And ye shall collect the waters" - There were two pools in or near Jerusalem, supplied by springs: the upper pool, or the old pool, supplied by the spring called Gihon, Ch2 32:30, towards the higher part of the city, near Sion, or the city of David, and the lower pool, probably supplied by Siloam, towards the lower part. When Hezekiah was threatened with a siege by Sennacherib, he stopped up all the waters of the fountains without the city; and brought them into the city by a conduit, or subterranean passage cut through the rock; those of the old pool, to the place where he had a double wall, so that the pool was between the two walls. This he did in order to distress the enemy, and to supply the city during the siege. This was so great a work that not only the historians have made particular mention of it, Kg2 20:20;Ch2 32:2, Ch2 32:3, Ch2 32:5, Ch2 32:30; but the son of Sirach also has celebrated it in his encomium on Hezekiah. "Hezekiah fortified his city, and brought in water into the midst thereof: he digged the hard rock with iron, and made wells for water," Ecclesiasticus 48.