Kai no Suna no Hakase-Kata

To remove sand from clams, the following technique works well: Place the clams in a colander and hang it over a bowl. Add salt water (1 tablespoon salt to 1 quart water) until the clams are barely submerged. Leave the clams in the bowl in a cool and dark place for 2 to 3 hours. Drain the clams, and rinse them under cold tap water.

The key to this technique is that the clams are suspended in the middle of the bowl of water and not placed on the bottom. This prevents them from taking in the ejected sand and other ejected material that collects on the bottom of the bowl.