If you have purchased or are using your own large tank and do not have access to insert a 1/” water barrel tap you can use a 1/2″ Top Hat Grommet. A 3/4″ hole is drilled at the bottom of the tank and the 1/2″ Top Hat Grommet is inserted into the hole. 1/2″ pipe is then pushed into the grommet. This will form a water tight connection.
AutoPot 1/2inch Top Hat Grommet