Soaking will Purge Clams or Mussels of Sand and Grit
The water, after removing the clams, will be quite silty.
Soak your shellfish -- in this case I had a 1-kilo, or 2 1/4-pound bag of clams -- in salted water in the refrigerator for several hours, or overnight; during this time they will purge themselves of sand and grit, which will be left behind when you remove them from the container.