What holds water yet is full of holes?

What belongs to you but others use it more than you do?

In former days my father and mother, Abandoned me dead, lacking breath
Or life or being. Then one began, A kinswoman kind, to care for and love me;
Covered me with her clothing, wrapped me in her raiment, With the same affection she felt for her own;
Until by the law of my life's shaping, Under alien bosom I quickened with breath.
My foster mother fed me thereafter, Until I grew sturdy and strengthened for flight.
Then of her dear ones, of daughters and sons, She had the fewer for what she did.