Why does my tank leak
Leaking tanks we've all had one there is many causes for this from simply not screwing the coil in tight enough to a complete dud coil. You maybe filling the tank from the wrong hole, you wouldn't be the first person to pour juice straight down the chimney instead of the fill hole. Running tanks well below the coil rating also can cause leaking due to the juice being drawn in thorough the cotton on inhale but not being vaporised.
Leaving juice in the tank for long periods (several days or weeks) without use especially in warm conditions will end in leaking, the cotton can only hold so much juice befor it will simply overwick and will not be able to hold anymore juice and it will simply run out the bottom of the coil. Left in a hot car the juice will become very thin and the cotton in the coil will not be able to hold the juice and once again it will just run out the bottom.
There are other reason as simple as you have damage a seal on the coil or on the tank itself or simply failed to tighten the tank down enough, what ever it may be a leaking tank is a pain, messy and at worst can damage your mod if it's bad enough. A couple of good quick videos we have found explaining a few reason as to why your tank maybe leaking can be found right here below