1/3 to 1cupnon-iodized sea salt or kosher salt, divided
Inspect clams. Discard any that with chipped or cracked shells.
If using hard shell clams, check to make sure that they're tightly closed. Gently tap any open clams on the counter and see if they close. If they remain open, discard.
If using soft shell clams (which won't fully close), tap or touch the side of the shell and/or siphon to check for movement. If the clam doesn't respond to the stimulus, it has perished and should be discarded.
Scrub clams under cold running water with a stiff brush to remove debris. If needed, use the tip of a paring knife to scrape off any barnacles.
In a large bowl or tub, combine 1 gallon of cold water with 1/3 cup of salt. Stir until salt is dissolved. Add clams, refrigerate, and let soak for 20-30 minutes. (The water should cover the clams by at least 1-1/2 inches). Discard any clams that float.
Lift clams from the bowl with a slotted spoon or your hands and discard water. If there is no sediment at the bottom of the bowl, the clams are ready to cook (common with cultivated and pre-purged hard shell varieties).
If there is sand/grit in the bowl, rinse and repeat the soaking process 1-2 more times (or more), depending on clam variety and how much sand the clams contain. Use 1 gallon of water and 1/3 cup salt each time, soaking for 20-30 minutes.
Place purged clams in a colander and rinse well with cool water. Cook clams as desired.
*If you want to add cornmeal to your soak (see blog post above), add about 1/4 cup medium-grind for every gallon of water.