Rashbam: Camels have two sets of knees, ¹ and, due to their height, one needs to kneel them twice before they are able to drink. ²

Oznayim la'Torah: He prepared them in advance so as to cut down the time they would have to wait when someone arrived to water them, in order to minimize their pain.

He had Bitachon that, the moment he finished his short Tefilah, the girl he was waiting for would arrive to fulfill his request.

Oznayim la'Torah: Because he wanted to pray a special Tefilah, something that he could not have done in Charan, which was full of idols. ¹

Malbim: Eliezer reasoned that one who would send his daughter outside the city to draw water, would not hesitate to send her to another land.

Oznayim la'Torah: People who lived in the Middle-East would make a point of always having a stock of cold water to counter the heat of the sun. To achieve this, they would draw water from the well towards evening, when the water from the underground streams is the coldest. ¹

Malbim: Eliezer sought a poor girl, for she would be more likely to consent to go with a slave to another land, to marry a rich, distinguished man. Only a poor man would send his daughter to draw water (rich men use slaves, or people who draw water for wages); especially towards evening, when men are around the well.

Oznayim la'Torah: Perhaps it is to hint that Eliezer was praying "l'Es Metzo" (Tehilim 32:6) for Yitzchak, which refers to a wife. ¹