If you have purchased or are using your own large tank and do not have access to insert a 19mm water barrel tap you can use a 19mm Top Hat Grommet. A 23mm hole is drilled at the bottom of the tank and the 19mm Top Hat Grommet is inserted into the hole. 19mm pipe (hosepipe) is then pushed into the grommet. This will form a water tight connection.
Please note that this product is sold individually.