threaded into threaded port 26 located in the base 24 of the skimmer 22 also connected in the base 24 of the skimmer 22 is a line 30 which is connected to the pump and filter unit of the pool during the winterizing step the drain 34 is open and the winterizing plug assembly 2 is inserted in the skimmer in the manner shown in fig3 an air pump 40 is connected to the air valve 10 and air is forced through the air valve under pressure into line 32 the air is initially discharged through the tube 12 air is forced into line 32 causing the air pressure in line 32 to increase this air pressure will force the level of water in line 32 to be lowered to a level generally indicated as 44 as can be seen level 44 is below the winterizing level 36 of the pool the water forced from line 32 is being discharged through the drain 34 into the pool in this way line 32 has been cleared adjacent the winter level 36 of the pool such that the pipe is less vulnerable to damage the level 44 within the line 32 is determined according to the air pressure within line 32 and the head of water in the pool determined by the level 36 in this way the user can depress the level of water in the line 32 and reduce the possibility of damage to the line 32 the winterizing plug 2 also has a number of benefits even if the seal or the valve.