Holesaw

If your water butt does not come fitted with a hole for a rain trap, these two items will come in handy. On the right of the photograph you will see a 25mm 'hole' saw. Next to it are the curiously named duo the 'drill & arbour' (sounds like some funny old pub). The arbour and pilot drill are designed to fit onto drills. Attach the 'hole' saw to the arbour and then drill the size of hole you need for the rain trap.

Even though they are sold separately, you will need both items.

Please check your drill can hold drill bits of 11mm shank