Where does “Pou” come from?

Pou (English) comes from Catalan pou, from Latin puteus, from Latin -al — noun-forming suffix.

Ancestry of “Pou”, step by step

Step	Language	Word	Meaning
1	Catalan	pou	well
2	Latin	puteus	pit, dungeon; well; cistern
3	Latin	-al	noun-forming suffix