2 Chronicles 32:2

And when Hezekiah saw that Sennacherib was come, and that he was purposed to fight against Jerusalem,

When Hesekiah saw that Sennacherib ... was purposed to fight against Jerusalem. An account of the means taken to fortify Jerusalem against the threatened siege is given only in this passage. The polluting or filling up of wells, and the altering of the course of rivers, is an old practice that still obtains in the wars of the East. Hezekiah's plan was to cover the fountain-heads, so that they might not be discovered by the enemy, and to carry the water by subterranean channels or pipes into the city-a plan which, while it would secure a constant supply to the inhabitants, would distress the besiegers, as the country all round Jerusalem was very destitute of water.