First, make sure that you followed the curing process for the barrel as indicated in the manual*:
*If you do not have a copy of the instruction manual, see bottom part of this article for a soft copy that you can download.
Make sure that you fill the barrel with liquid right away because if you leave the barrel empty and unused, the wood will dry out and possibly leak when you use it again. You will need to repeat the curing process to reseal the barrel if this happens.
The location where you put the barrel also affects the wood expansion. Keep it out of direct sunlight in a cool (55°F – 60°F) and optimally humid (65% - 75%) area.
If the barrel is still leaking after following the curing instructions, submerge the barrel in water for a couple of days. After it's been submerged, dry the exterior with a towel and fill it with water to see if it continues to leak. If so, find the leak and apply a generous amount of barrel wax to the hole.
Feel free to contact us at guys@mancrates.com if you need further help with this issue.