Simple answer:
Leave it to stand for long enough and the sand will settle to the bottom of the jar whilst the water stays on top.
Geologists answer:
The technical definition of sand is sediment between the diameter range 0.0062mm to 2mm so if you have a sieve finer than 0.0062mm then you can sieve the mixture and separate the sand from the water!
Comments
asheydude345 commented on :
the Geologist answer is totaly not needed