to fill one's water bottle at a water refill station
to refill one's water bottle at a water dispenser
「冷水機で水筒に水を入れる」ことは次のように言えますよ。
ーto fill one's water bottle at a water refill station
ーto refill one's water bottle at a water dispenser
例：
I was so thirsty I was glad to find a water dispenser so I could refill my water bottle.
「すごく喉が渇いていたので、水筒の水を補充できる冷水機を見つけて嬉しかった」
ご参考まで！
カナダ 
