Ye have seen also the breaches of the city of David, that they are many: and ye gathered together the waters of the lower pool.
Ye have seen. The prophetic preterite.
The breaches of the city of David - the upper city, on Zion, the south side of Jerusalem (2 Samuel 5:7; 2 Samuel 5:9; 1 Kings 8:1); surrounded by a wall of its own; but even in it there shall be "breaches." Hezekiah's preparations for defense accord with this (2 Chronicles 32:4-5).
Ye gathered together the waters of the lower pool - (note, Isaiah 22:11.) Ye shall bring together into the city, by subterranean passages cut in the rock of Zion, the fountain from which the lower pool (only mentioned here) is supplied (note, Isaiah 7:3; 2 Kings 20:20, "he made a pool, and a conduit, and brought water into the city." 2 Chronicles 32:3-5 represents Hezekiah as having stopped the fountains to prevent the Assyrians getting water. But this is consistent with the passage here. The superfluous waters of the lower pool usually flowed into Hinnom valley, and so through that of Jehoshaphat to the brook Kedroo. Hezekiah built a wall round it, stopped the outflowing of its waters, to debar the foe from the use of them, and turned them into the city.