Trap primers and trap protection devices protect and maintain the water seal in fixture traps, preventing the entry of sewer gases into occupied spaces. Water traps in plumbing systems can be lost due to evaporation, infrequent use, or pressure fluctuations. A trap primer automatically replenishes the trap with a small amount of water to preserve this seal, while barrier-type trap protection devices slow/prevent evaporation and block sewer gas intrusion. Trap primers can be activated by pressure changes (mechanical type), sensors/timers (electronic), or by using gray water from a nearby lavatory drain (gravity fed). Trap primers are often required by plumbing codes for floor drains in remote areas or other infrequently used fixtures.