1. Bridging occurs in water softening when salt sticks together to form one large solid mass of pellets, or by the salt caking in a dry-salt brine tank which causes failure of the liquid or brine beneath the dry salt to become saturated. The result of bridging is insufficient salt in the regenerant solution to properly regenerate the cation resin. 2. The ability of particles to form a crustlike film over void spaces within a filter medium or membrane.