standing water: a natural pool, pond, or reedy marsh where water collects and sits rather than flowing or springing up
This is water that has nowhere to go. It gathers in a low place and stays there, so its edges blur into mud and reeds instead of making a clean shoreline. That is why English Bibles reach for two different words for it, sometimes "pool" and sometimes "marsh", depending on whether a verse is looking at the water or at the soggy ground it soaks.
Two neighboring Hebrew words fix the difference. A בְּרֵכָה is a pool people dug and lined to hold water for a town, and a מַעְיָן is a spring, where water pushes up out of the ground and keeps moving. This word is neither. Isaiah 41:18 and Psalm 114:8 set it beside the word for a spring in the same breath, which shows the writers heard the two as different things.
Most of the nine places it appears fall into two pictures:
- the standing water of Egypt, listed with the Nile and its canals when the plagues fall on everything the country drinks from
- the promise that God will turn scorched ground into a pool, so that water lies where nothing could live before
The second picture carries the weight. Isaiah 35:7 says the burning sand will become a pool, and Psalm 107:35 and Psalm 114:8 say the same of desert and bare rock. Turn the image around and you get judgment instead: Isaiah 42:15 dries the pools up, and Isaiah 14:23 leaves proud Babylon as nothing but swamp.