|1.||leaks like a sieve|
phrase commonly used to say that something is leaking profusely when it is not supposed to leak at all. A sieve is a wire mesh or perforated metal utensil used for straining or sifting. Therefore anything that is leaking like a sieve is not holding water at all.
I have tons of water damage from the rain. My roof leaks like a sieve.
|2.||leaks like a sieve|
This generally refers to something not being able to retain fluid. A sieve is a piece of wire mesh, used to strain larger objects from fluid. Similar to a colander or strainer.
My nose leaks like a sieve, because I am sick.