Abstract: A safety valve for swimming pools that senses and then instantly relieves excessively high vacuum levels in the pool's drain line. Such high vacuum levels occur when an individual becomes trapped by the suction at the pool's drain port which is connected to the drain line. The valve relieves the high vacuum level in the pool's drain line and the suction at the drain port by bleeding air into the pool's drain line, causing the pump connected to the drain line to lose prime. The valve is equipped with means for adjusting the vacuum level at which it actuates to accommodate varying vacuum levels found at different pools.