Well
noun
A well door is just a well. It's the door that goes into the well hole, making it a well.
いど
This kanji uses the kun'yomi readings for each kanji, for some reason. You learned the kun'yomi reading for both of these kanji as their primary readings already, just watch out for 戸 getting rendaku'd so it becomes ど instead of と.
あそこに井戸があるよ。
There's a well over there.
井戸に入ってはいけないよ。
You must not go into the well.
え、今、井戸から声がしなかった?
Wait, didn't you just hear a voice coming from the well?
この井戸の水は飲み水ではありません。
The water from this well is not drinking water.
よくひえた井戸水を飲むと、つめたいアイスクリームを食べた時のように頭がキーンといたみました。
When I drank cold water from the well, I got brain freeze like when I ate cold ice cream.