# Vape tank: the complete guide for UK vapers > Glass, PCTG or plastic, the 2 ml cap, filling, maintenance and leaks: understanding the vape tank on your device, and looking after it properly. A vaper changing hardware almost always looks at the coil first and almost never at the tube holding it. Yet that tube governs how often you refill, how well the thing seals, and a good share of the leaks reported at shop counters. Understanding what a **vape tank** really covers saves a lot of disappointment, at the moment of choosing as much as in day to day upkeep. ## What a vape tank actually is The tank is the clear part that stores e-liquid before it reaches the coil. Together with the coil and the air chimney it forms the assembly screwed onto the mod or the battery, which British listings call a tank and older writing sometimes calls a clearomiser. Its transparency is not decorative. It lets you watch the level without stripping anything down, and stops a coil heating dry for want of liquid, which damages it immediately. An empty **vape tank** is spotted at a glance, before any burnt taste arrives. Three parameters between them decide most of the everyday experience: capacity, material and filling method. Everything else on a spec sheet is secondary to those. ## Glass, PCTG or plastic: what the tube is made of Three families of material share the market, with fairly clear trade-offs between toughness and lightness. None of them is best in the abstract. Borosilicate glass, often listed as pyrex, remains the most widespread material on mid and upper range reservoirs. It stands up to heavily flavoured or alkaline liquids, which eventually weaken some plastics. Its weakness is impact: a fall on a hard floor can crack it where a plastic tube would survive. PCTG, a glycol modified copolyester, equips many recent tanks, particularly models aimed at travel or heavy daily use. It is effectively unbreakable in normal use and lighter than glass, at the price of slightly lower chemical resistance over the very long term. Standard plastics of the polycarbonate type equipped a large share of older budget reservoirs. They are now a minority on new references, replaced by PCTG for comparable durability at a similar manufacturing cost. ## Capacity and the 2 ml cap in the UK This is the point most often misunderstood, and the one that makes overseas reviews misleading. Under the Tobacco and Related Products Regulations 2016, administered by the MHRA, e-cigarette tanks sold in the United Kingdom are restricted to a capacity of no more than 2 ml. The cap applies to the reservoir the user fills, whatever it is called on the listing, whether tank, pod or cartridge. The same regulations restrict nicotine containing e-liquid to 10 ml per refill container and to a strength of no more than 20 mg per ml, require child-resistant and tamper evident packaging, and require notification to the MHRA before a product can be sold. So a compliant reservoir on a British shelf states 2 ml, even where the same model exists in a larger version on other markets. Some designs reach that figure with an internal bung or a shortened tube inside a body of unchanged size, which is why two versions of one tank can be visually identical. That constraint explains a higher refill frequency here than in reviews filmed elsewhere, and it makes filling ergonomics a real criterion rather than a detail. It applies to refillable pod formats in exactly the same way. ## Top filling or bottom filling Two filling mechanisms coexist, with opposite handling logics. One of them has become close to universal on new hardware. The great majority of recent tanks fill from the top: you unscrew the upper cap or slide a cover, without touching the base or the coil. The bottle goes straight into the opening, and you stop short of the maximum level marked on the tube. That system limits handling and removes the risk of unscrewing the coil along with the reservoir. Some models, often older or oriented towards rebuildable use, require unscrewing the whole base to reach the reservoir. Liquid then has to run down the inner wall, never straight into the central chimney, on pain of flooding the coil and producing gurgling in use. ## Routine maintenance of a vape tank Regular upkeep noticeably extends the life of a **vape tank** and heads off leaks. Three habits cover the majority of cases, and none of them takes long. At every coil change, rinse the reservoir in clean water, let it dry completely in open air, then check the state of the visible O-rings. A split or missing seal is the leading cause of leaks at the joints, and it is a part sold cheaply as a spare. Roughly every other time, strip the assembly completely: tube, base, drip tip and airflow ring are cleaned separately in warm water, never with an abrasive household product. Dry each piece carefully before reassembly, because a tube still damp encourages marks and micro bubbles at the next fill. Never immerse the electronic part, mod or battery, even partially. Only the tank, fully separated from its support, should meet water at all. ## The main causes of a leak On a reservoir in good condition, a leak almost always comes from one of four origins, to be checked in this order before blaming the design. - A worn, split or absent O-ring at one of the joints of the reservoir. - Filling too fast or too high, which leaves insufficient air pressure inside the tube. - An airflow ring left open during filling, which unbalances the internal pressure. - A coil screwed in badly or at the end of its life, whose thread no longer seals. Closing the airflow before opening the reservoir, then reopening it only after the cap is back on, removes a large share of the pressure swings responsible for leaks at filling. It is the single most useful habit on any top filling design. ## When to replace the tank rather than repair it A tank is rarely replaced as a whole, but some signals justify a full replacement rather than a repair. Recognising them avoids both waste and a nasty surprise. A visible crack on a glass tube, however small, calls for immediate replacement: weakened glass can give way suddenly when tightened or after a light knock. A rounded thread that no longer holds the coil or the base properly, despite new seals, marks a part at the end of its mechanical life. Persistent discolouration of the liquid in the reservoir, despite repeated rinsing, often reflects a porosity in the plastic that has absorbed flavourings deeply. In that case changing only the tube, frequently sold on its own by manufacturers, is enough without replacing the base or the coil. ## FAQ ### Why does my tank gurgle when I vape? That noise generally arrives when liquid has worked its way into the central chimney. It reflects an excess of liquid at filling or a coil at the end of its life with a saturated wick. ### Can a reservoir larger than 2 ml be sold in the UK? No. The regulations cap any refillable tank legally sold on the British market at 2 ml, whatever the model or the brand. ### Is glass more fragile than plastic? Against impact, yes: glass can crack where a PCTG tube survives. Against concentrated liquids it is the reverse, glass keeping its clarity and its seal better over time. ### How often should a tank be cleaned? A quick rinse at every coil change, and a full strip down roughly every other time, cover the majority of everyday use. ### Is a leaking tank always for the bin? No. Most leaks come from a worn seal or a mishandled fill, two causes corrected without replacing the tube. Replacement only becomes necessary with a crack or a damaged thread. ## What to remember about your vape tank Choosing a **vape tank** comes down to three simple questions: which material for which use, which filling method for your daily habits, and how easily you can still buy the coil in a year. Capacity settles itself here, since every compliant reservoir holds 2 ml. Regular upkeep, seals checked and parts properly dried, resolves the great majority of leaks before they appear. That is worth more than any feature listed on a box, and it costs nothing but a few minutes at each coil change. To go further on [e-liquids and their ratios](/uk/e-liquid-guide/), or to compare how [the Vaporesso iTank T organises its top airflow](/uk/vaporesso-itank-t/), the other guides on the site set out compatibility brand by brand, starting with the [Aspire range](/uk/aspire-vape-tank/). Read the range printed on your coil before anything else, and the rest of the choice around your **vape tank** falls into place on its own. This article is strictly informative and is written for adult vapers only. It is not a buying recommendation: depending on the reference, a vaping product contains nicotine, a substance that causes dependence. Nothing described here may be sold to under-18s in the United Kingdom.