This is the 11035th most frequent Turkish word.
doldurularak
"Filled by filling" or "filled by being filled."
Here, 'doldurularak' is used to indicate the method or action (filling out the form) required for the process to be completed.
Formu doldurularak işlem tamamlanabilir.
The process can be completed by filling out the form.
In this sentence, 'doldurularak' describes how the bottle was prepared—through the action of being filled with water.
Şişe suyla doldurularak hazır hale getirildi.
The bottle was prepared by being filled with water.
The usage of 'doldurularak' shows the method by which the bucket becomes ready for its purpose—by being filled with water.