Ye made also a ditch between the two walls for the water of the old pool: but ye have not looked unto the maker thereof, neither had respect unto him that fashioned it long ago.
Ye made also a ditch - a reservoir for receiving the water of the old pool. Hezekiah surrounded Siloah, from which the old (or king's, or upper) pool took its rise, with a wall joined to the wall of Zion on both sides. Between these two walls he made a new pool, into which he directed the waters of the former, thus cutting off the foe from this supply of water also. The opening from which the upper pool received its water was nearer Zion than the other, from which the lower pool took its rise, so that the water which flowed from the former could easily be shut in by a wall, whereas that which flowed from the latter could only be brought in by subterraneous conduits (cf. note, Isaiah 22:9; Isaiah 7:3; 2 Chronicles 32:30; Sir 48:17). Both were southwest of Jerusalem.
But ye have not looked ... neither had respect - answering by contrast to, 'thou didst look to the armour, ye have seen (had respect, or regard to) the breaches' (Isaiah 22:8-9.)
Maker thereof - God, by whose command and aid these defenses were made, and who gave this fountain "long ago."