A trap primer is a valve that adds water to traps. The water in the trap is needed to prevent methane gas that rises from the sewer line from entering buildings. The water can evaporate however. The evaporation is slowed by using natural oils on the drain to barely cover the trap's "water surface". When oil and water are mixed, oil floats to the top, in effect creating a floating seal maintaining the water in the trap. It's recommended to use mineral oil, as mineral oil doesn't go rancid. The trap primer therefore is necessary to maintain the water levels. | A trap primer is a valve that adds water to traps. The water in the trap is needed to prevent methane gas that rises from the sewer line from entering buildings. The water can evaporate however. The evaporation is slowed by using natural oils on the drain to barely cover the trap's "water surface". When oil and water are mixed, oil floats to the top, in effect creating a floating seal maintaining the water in the trap. It's recommended to use mineral oil, as mineral oil doesn't go rancid. The trap primer therefore is necessary to maintain the water levels. |