Everything else Hezekiah did while he was king, including how he made the upper pool and tunnel to bring water into Jerusalem, is written in The History of the Kings of Judah.
the Babylonian troops broke through the city wall. That same night, Zedekiah and his soldiers tried to escape through the gate near the royal garden, even though they knew the enemy had the city surrounded. They headed towards the desert,
Nehemiah son of Azbuk ruled half of the district of Beth-Zur, and he rebuilt the next section of the wall. It went as far as the royal cemetery, the artificial pool, and the army barracks.
You are in for trouble if you go to Egypt for help, or if you depend on an army of chariots or a powerful cavalry. Instead you should depend on and trust the holy LORD God of Israel.
Sennacherib, now listen to me, the LORD. I planned all this long ago. And you don't even know that I alone am the one who decided that you would do these things. I let you make ruins of fortified cities.
Then the LORD said to me: Take your son Shearjashub and go and see King Ahaz. You will find him on the road near the cloth makers' shops at the end of the canal that brings water from the upper pool.
When King Zedekiah and his troops saw that Jerusalem had been captured, they tried to escape from the city that same night. They went to the king's garden, where they slipped through the gate between the two city walls and headed towards the valley of the River Jordan.