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My Tank Keeps Leaking, What’s Wrong with It?

As a vaper, there are few things more annoying than a leaking tank. Unfortunately, it’s virtually inevitable, so you might as well get used to the thought that sooner or later you’re going to run into this problem. Luckily, there are a few things you can do to prevent tanks from leaking or at least minimize the damage. The most important of these is knowing what can cause your tank to leak, and, believe it or not, there are quite a lot of causes, from the way you handle the tank to the type of juice you’re using.

I’ve put together a list of things that are most likely to cause leaking problems, as well as a few tips to help you prevent these frustrating leaks. That’s not always possible, as some tanks and coil-heads are simply defective of have design faults, but these tips can help you prevent leaks caused by human error. Anyway, here we go:


Choosing the Right E-Liquid Viscosity – High propylene glycol (PG) e-liquids are considerably thinner that vegetable glycerin (VG) based ones, and knowing which to use in what type of tank can help you prefer leaking.

Advanced sub-ohm tanks usually come with clear instructions that they should only be used with thicker juices (70% VG and over), while mouth-to-lung tanks, which generally use high-resistance coil-heads (1 ohm and over) work well with PG-based e-liquids. Vegetable glycerin has a higher viscosity, so sub-ohm coils-heads generally have large wicking holes to make it easier for the thicker juice to reach the heating elements. PG juice, on the other hand, is much thinner and would simply flood sub-ohm coils, with the excess juice eventually leaking out of the tank.

Using high VG e-liquid with mouth-to-lung (MTL) tanks is not a good idea either. It may not result in leaking, but the tiny wicking holes would most likely prevent enough juice from reaching the coil, which can lead to nasty dry hits.

Make sure to always check the label on your e-liquid bottles to determine the PG/VG ratio.

Adjust Your Power Output – Low power output is the least likely culprit when it comes to leaky tanks, but it’s actually one of the most common causes. The reason is pretty simple if you know how atomization works. When you draw, e-liquid from the tank gets sucked into the coil-head/RBA and vaporized by the heating element, but if the coil doesn’t get hot enough, excess juice build-up in there and eventually starts to leak through the airflow holes.


A sign that you need to increase your wattage is gurgling when you draw. Bumping up the power will vaporize the excess juice, but if you ignore the gurgling, you’ll likely have to deal with some nasty leaks.

Constantly Check the O-Rings – Damaged, worn or missing o-rings are one of the most frequent causes of leaking. These tiny rubber rings play a vital role in keeping the e-liquid contained in the tank, but they lose their sealing properties over time time and are also prone to damage by over-tightening the tank. My biggest problems with o-rings is that they often come off when washing the tank, and most times you don’t even know they’re missing until it’s too late.

You don’t need to check the o-rings every time you clean your tank, but it’s recommended to check on them every once in a while. Also, be careful when putting the tank back together, as you can accidentally over-tighten them and damage the o-rings in the process.

Fill the Tank Properly – This sounds like a no-brainer, I know, but you would not believe how many beginner vapers do it wrong the first few times. Obviously, filling the central air-shaft of the tank with e-liquid is the most common mistake, but it’s definitely not the only one. For some reason, that narrow hole is a lot more appealing than the glass tube itself, but it’s the last place you want to be dripping juice into. You’ll end up flooding the coil-head or the wicking, and all the excess juice will leak out of the tank through the bottom airflow slots.

You also don’t want to fill the tank all the way up. Leaving a bit of air at the top helps create a vacuum inside the container, which prevents the juice from leaking out.


Faulty Tank/Coil-Heads – Manufacturing defects are not as common as some people would have you think, but they do rarely occur, and there’s not much you can do about it. Most often that not, it’s the coil-heads that are faulty – meaning that they just leak by design, or they are not properly insulated – but I’ve also had a few tanks with dodgy threading that made containing the juice inside impossible. When dealing with faulty hardware, you’re best option is to take them back to the shop for a refund. You should make sure that your coil-head is crewed on properly and that the various tank seals are nice and tight, but if that doesn’t solve the problem, there’s not much else you can do.

Check for Tank Damage – In order to properly contain the e-liquid inside, a tank has to be air-tight, and any kind of damage can prevent that. Whether it’s very small cracks in the glass tube, or a slightly bent or dented metal part can, damage can potentially lead to leaks. Obviously, your greatest concern should be for the glass part of the tank, because it’s the most vulnerable. Even a small knock on a hard surface can produce a crack, and once that happens, you’re only option is to replace it. Luckily, most advanced tanks nowadays come with a spare glass tube, but silicon vape bands also so a great job of protecting the glass.

If you accidentally drop your mod, check the glass for cracks. Sometimes they are so small that they are hard to spot, but they will inevitably cause the tank to leak.

Learn to Wick Properly – This applies to RBAs, RTAs, RDTAs and whatever other atomizers require re-wicking. If you only use coil-heads, you might as well skip this section.

Wicking is the single most important part of setting up your atomizer. Using too much cotton, or cramming the leads into the wicking holes is going to prevent leaks, but it will also make it harder for the juice to reach the coils. If you’re lucky, that only mutes the flavor of your vape, but it can also cause dry hits – those nasty mouthfuls of foul smoke from the burned cotton. Dry hits usually occur when the cotton wick is not saturated with e-liquid.


But if you use too little cotton, or fail to cover the wicking channels of your atomizer completely, too much liquid will make its way into the atomization chamber, flooding it and eventually pouring out if the tank through the airflow slots.

‘Balance’ is the key word when it comes to wicking. You want the cotton to seal off the wicking channels, but you don’t want your leads to cover the juice holes completely. Also, you want to keep your leads just thick enough to loosely fit into the channels, as they’ll expand a bit more when they fill up with e-liquid. This is only a bit harder to do in the beginning, but you’ll get the hang of it before you know it.

Keep Your Tank Vertical – When your tank is in vertical position, its wicking holes are covered with juice, which maintains the vacuum effect inside the coil-head/RBA base, but when it is on its side, at least one of the holes is exposed, and you don’t want that.

Keeping the tank in a horizontal position for short periods of time – like storing it your pocket for a few minutes – is not a problem, but if you leave it like that for a long time, it will start to leak at some point. This really isn’t anything to worry about when you’re using a box mod, because it’s easy to set them upright on a flat surface when you’re not using them, but cylindrical devices like the SMOK Brit One and most mechanical mods are another matter. Their narrow base makes it harder to keep them upright all the time, but you have to make sure that the tank doesn’t remain on its side for too long.

The least you can do is keep the tank straight overnight. If you can’t set your mod upright before you go to bed, at least detach the tank and make sure you it’s sitting vertical. The important thing is to keep the tank horizontal as little as possible.


These are the most common causes of leaking, but as I mentioned in the beginning, as much as you try to prevent them, leaks will happen occasionally. Whether it’s faulty hardware or just user error, it’s one of these things that will occur at some point. Apart from using the tips I mentioned above, your best way to prevent leaks is to use a leak-proof tank, like the Joyetech Cubis or the OBS Engine. This type of tank only has top airflow, and their bottom section is perfectly sealed, so there’s no way for juice to spill onto your mod. However, it has its own weakness. If juice does build up into the coil-head/RBA base, there’s only one way it can go, and that’s up, through the central shaft and into your mouth. So you basically have to make a choice between having e-liquid spill through the base, or potentially getting some hot droplets of it into your mouth.


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