What does Genesis 26:18 mean?
Isaac, though enormously wealthy (Genesis 26:12–13), has a problem. He has been sent away from the area directly around Gerar by King Abimelech. He has grown too large and powerful to stay without being a threat to the Philistines in the region (Genesis 26:14–16).Isaac's choice, shown in this verse, seems to balance the wishes of king Abimelech with his obedience to God. Earlier, God told Isaac to stay in Gerar rather than seeking better land in Egypt (Genesis 26:2–3). So, Isaac settles in the Valley of Gerar, which presumably is further from the majority of the people, but still in the same general area.
Isaac must quickly find water to support his herds, flocks, and large company. What he finds are the old wells that had belonged to Abraham when he lived in this same region (Genesis 21:25–27). They had been filled in, presumably after Abraham died. Isaac reopens them and begins calling them by the names Abraham had given to them (Genesis 21:23–33).
The fact that these wells were given unique names, and that they were stopped up by the Philistines, indicates just how precious water and water rights were in this arid region of Canaan.