How to Fill a Scuba Tank the Right Way: Complete Guide

One of the most important pieces of equipment to get right when scuba diving is the air tank. Being able to breathe under water in a highly pressurized environment requires equipment that is reliable to upholds the highest standards of safety. Properly filling a scuba tank ensures that the air is of high quality and at the proper pressure – and that the tanks are in usable condition. 

What is the right way to fill a scuba tank? To fill a scuba tank, the tank needs to be inspected, and pressure regularly tested, placed in cold water to identify the damage, and set up at a specific scuba or highly pressurized air compressor at 3,000 psi to fill. 

These are the steps to filling a scuba tank the right way: 

  1. Tank inspection 
  2. Dispose of faulty tanks 
  3. Drain extra air from the tank 
  4. Turn on air compressor 
  5. Attach an air compressor to the tank 
  6. Fill scuba tank 
  7. Release air and remove compressor yoke 
  8. Safe tank storage 

Understanding how to safely fill a scuba tank is crucial so divers can enjoy their adventures with no tank-related problems. You need these systems to be dependable, and a scuba shop can best identify this for you. We will go through the steps necessary to fill a scuba tank the right way, whether that be on your own or choosing professional tank filling. 

Can You Fill Your Own Scuba Tank? 

Instead of having to take your tanks into a dive shop when they need a refill, you may want to do it yourself. While it does not require many steps to fill a tank, it does require specific equipment that is expensive to acquire. You need to purchase specific air compressors and filters that most people do not have if you plan on filling scuba tanks yourself. 

Standard air compressors that are found in your garage or sold at hardware stores typically do not reach over 200 psi, which will be suitable for most household tasks. Scuba tanks need to generate pressures upwards 3,000 psi to be effective for underwater use. Purchasing an air compressor that is equipped to satisfy these requirements would cost you over $2,000. 

If you do choose to invest in the equipment, you will save money from fill up fees only if you are an avid scuba diver and plan to be for a long time. It will take lots of refills to make up for the initial price you paid for the air compressor. You could fill up your friends’ tanks to make it worth the investment too!  

Make sure you are certified as many dive shops may not be willing to sell you the necessary equipment until you can provide proof that you have been properly trained in scuba diving safety. Scuba diving can be a very dangerous activity if safety protocol is not adhered to. Having these certifications is necessary to ensure proper training. 

Steps to Filling a Scuba Tank the Right Way

Whether you fill the tank yourself or have it done professionally, the same steps need to be taken to complete the job safely and correctly. Attention to these details is crucial so that you not only refill the tanks without danger but also so it will be functional when needed in the water. 

1. Tank Inspection 

Before you do anything related to air, you will want to inspect the tanks beforehand. Checking for damage and pressure is crucial for safe filling as well as ensuring that the air will not leak from the tank afterward. When scuba diving, there are plenty of opportunities for the tank to come in contact with other equipment or rocks that may cause damage. 

These are the different steps you should take to check your tank for damage or wear: 

  • Visual inspection: You can perform a visual inspection on the tank to look for dents and any markings that look out of place. Carefully examine the exterior tank, gauges, and valve for imperfections and potentially more serious changes to the surface. 
  • Sound inspection: Scuba tanks need to remain dry to be effective, meaning that if there is water or debris inside, they should not be used. Gently shake the tank to listen for any movement of liquid. If you the water moving around, you should not use or fill the tank. 
  • Place in cold water: Placing the tank in cold water can help to identify cracks that may be too small to catch while glancing the tank over. If you see bubbles after the tank has been submerged, there may be a leak in your tank. This is also used to keep the tank cool once it is filled so that hot air being put inside does not damage the tank or lead to accidents. 

Tanks that are leaking area or have been damaged should not be used. When they are submerged and used during a scuba excursion, these tanks can crack further with increased underwater pressure and be dangerous. If these accidents occur at deep water levels, there can be serious or fatal situations.

Inspections should also be completed regularly by a dive shop or professionals to test the tank pressure. These tests are known as hydrostatic tests and should be completed at least once per year. It is required to have them tested every five (5) years, but more frequent use should increase the frequency in which you have them tested. 

Hydrostatic tests include a visual inspection of the cylinders (where the pros know exactly what to look for), a pressure test to hold the right air pressure, cleaning, and full service. This pricing will range based on the services provided and location of service, but you can expect to pay an average of $50, with some stores being cheaper and much more expensive. 

Checklist before filling a scuba tank

2. Dispose of Faulty Tanks

If you have identified that a tank has been damaged or is not in complete working condition, you should dispose of the tank as it is not fit for use. When underwater, you want a tank that will be reliable, and this can be compromised if you notice cracks or holes in the tank. These may also be tanks that do not pass the hydrostatic or visual tests at a local dive shop. 

To dispose of your tanks, the dive shop can take these tanks from you directly. Especially if the tank does not pass inspection, these tanks are often turned over and sold for scrap metal. The valve is often still in good condition, and this can be resold by the dive shop. Because they can make use of the faulty tanks, the dive shops will typically take the tanks free of charge. 

You can also take these tanks directly to a scrap metal dealer that can pay you for the tank. In these cases, the tank will need to be completely emptied, and the valve removed. They can only make use of the cylinder itself, and by removing these other elements, you reduce any safety risk that may occur with air still in the tank. 

Scuba tanks are generally long-lasting, ranging in life span based on the quality and the type of tank. Your tank should last well over ten (10) years unless they come in direct contact with another object and get damaged. This means that you will not need to replace or get rid of old or damaged tanks frequently. 

3. Drain Extra Air From Tank

Also known as bleeding air out, you will want to release some old air from a tank to make sure that you do not over pressurize it, which could cause damage. 

Tanks should also have air released when they have been left unused for over three (3) months, especially if steel tanks as the oxygen content could no longer be safe. Releasing air will depend on the quality of your tank and type. Keep around 200 psi in the tanks, so they do not accumulate moisture.  If there is no pressure in a tank, this could lead to moisture finding its way into the tank and increase the probability of rust developing. 

When refilling, letting out extra air will not allow moisture to develop in a short amount of time until you fill it completely. To release air from the scuba tank cylinder, you will want to follow these instructions: 

  • Slowly open the air valve: You do not need to open this very far to let air out. It is best to just crack open the valve to let air release slowly. This prevents any moisture from collecting that may occur when air is released too quickly. 
  • Understanding tank weight: You will want to release air from a tank as an air compressor may fill it too full during a scuba tank fill up. You will want to let air bleed out slowly unless the tank is under 10 pounds of pressure. 
  • View pressure gauge: You can also use a pressure gauge on the tank to see what the current level is at and release air accordingly. These gauges are also used during scuba diving, so you know how much air is left in your and when you should come up. 

The key when letting air out of a tank for any reason is to do so slowly. This keeps your tank in the overall best condition to not let any debris or additional materials into the valve when it is opened. Keep the valve opened only slightly during this process. 

4. Turn On Air Compressor 

Now you are ready to start working with the air compressor. Keep in mind that this machine is specifically designed for highly pressurized air, and you cannot use a standard air compressor that could be found at a hardware store. These compressors not only provide much higher levels of air pressure, but they are also equipped with filters that remove harmful compounds. 

Filtering the air is one of the most important components because it allows for clean air to be collected in the tanks and useable for safe breathing while scuba diving. Once this is connected to the air compressor, you will want to turn it on and make sure it is at the appropriate pressure and size settings. 

Make sure the air compressor is set up to fill up your specific tank to the desired pressure reading. Some tanks may require different pressure settings than others, so you will need to refer to your tanks guidelines before attempting to fill. Most tanks are filled to around 3,000 psi or slightly higher. 

Most air compressors will have an automatic shut off setting once the tank reaches a certain pressure setting. You will want to take advantage of this feature as to not fill the tank too full, which can lead to potential tank damage. 

5. Attach Compressor to Tank

There will be a hole on your scuba tank that is compatible with an air compressor hose. Some hoses may be specific to different sizes and types of tanks, so make sure the one you use will fit securely. If you take your tank to a dive shop, they will have the right hoses on their air compressors to attach to the hole on the tank. 

Attach the hose, known as a yoke, onto the tank and make sure this connection is secure. Be careful not to strip any of the metal on either piece by carefully fastening the two together. 

This will ensure that no air can escape, and other outside materials cannot find their way into the tank. 

Once this is tightly sealed, you can turn on the hose, which will begin to fill the tanks. When you do turn the nozzle on the hose, make sure you do so with slow and careful turns. This will prevent equipment from braking and ensure a steady flow of air into the tanks. 

6. Fill Scuba Tanks 

Air compressors produce a great amount of heat and can be really noisy once you use them. The method of giving your scuba tank a cold bath can be useful to make sure that the tank does not overheat during this process. The sound factor can be minimized by enclosing the compressor in a structure so that you can help deflect some of the noise that is produced. 

As long as you are using the proper equipment (including air compressor and filters), the actual filling is the easiest part. Even if you have the automatic shut off feature engaged on the air compressor, you should still be watching in the event that it does not trigger. You can also manually shut off the hose once your tank reaches the desired level of pressure. 

This process should be done steadily and slowly to ensure that air is being taken in a controlled manner. Filling up the tank too quickly could lead to problems associated with being overfilled and damaging either the tanks or the valves in the process. 

7. Release Air and Remove Air Compressor Yoke 

Once you have filled your tanks to the desired pressure, you will want to make sure all valves are closed and carefully remove the hose from the air compressor. Doing so carefully will prevent any damage that can occur to the valves if the components scrap against one another or are removed quickly. 

Allow the scuba tank to sit for a few minutes to ensure that it is not hot before moving. Ideally, you will want to fill your tanks away from heat as not to cause accidents or make them too hot to move in warmer temperatures. Because this process does not take long, you shouldn’t have issues with overheating while transporting the tanks after a fill. 

If you are going to a dive shop, this process will likely be done indoors and ready to take back home with you right after filling. Some dive shops may outsource this entire process, which may force you to wait to get your tanks back a little later. If you do not need them immediately, this may be a less expensive option for tank filling. 

8. Safe Tank Storage 

After you fill your tank, you will want to make sure it is safely stored until you head back out into the water. This is an important last step to ensure that no damage occurs to the tanks, which would take you back to step two (dispose of faulty tanks). These are the most crucial things to remember when storing your dive tanks: 

  • Store upright: You do not want your tanks to be stored on their sides because this can alter the composition of the gas inside, and if there are small traces of water, they may spread to a larger area. This can lead to issues of rust and corrosion. You can lay tanks on their sides when transporting or using them, but storage should be upright. 
  • Secure tanks: Because there may be a chance for an upright tank to be damaged when knocked over, you should make sure the tanks have little room to move or bump into one another. Pushing something up against them or keeping towels in between the tanks can help to prevent them from damage. 
  • Avoid heat: Keeping your tanks in excessive heat can be dangerous because the internal temperature of the tank will increase. This may lead to the expansion of the gas and, in worst cases, rupturing. Explosions are dangerous and may cause damage or injury to the nearby surroundings. 

Taking care of your scuba tanks is a crucial step in allowing your tanks to be filled correctly. We also recommend properly cleaning your tanks after you go scuba diving to keep them in the best shape possible. Debris and saltwater can be hard on the tank and create build up on the tank, which may make holes and cracks harder to identify. 

How Much Does it Cost to Fill Up a Scuba Tank? 

It is very inexpensive to fill an air tank at a scuba store or air supply provider. If you head to your local dive shop or scuba retailer, it should cost you around $5 to fill a scuba tank. If you refill your tank at a scuba shop, you may also be able to get your tank pressure tested as well. If you pay for the cylinder testing (usually around $50), you may get the air fill for free. 

If you do hire professionals to fill your tanks for you, there are a couple of things you will need: 

  • Scuba certification: Scuba diving shops will not typically sell or refill tanks unless you have a scuba certification you can show. Scuba diving is a dangerous activity that should not be done without completing a scuba diving course. Once you have your certification, it means you are up to date on the necessary education and can operate your equipment safely. 
  • Tanks to refill: You can purchase tanks from a scuba shop and get them refilled as long as they are in good and working condition. There will be labeling on the tank that notes when the last hydrostatic test was completed, and a shop will only fill the tank if this test has been completed. 

Scuba tanks refills may fluctuate in price depending on the size and where you buy them. Scuba diving shops or paintball fields are typically the best places to find these tanks. You can check here for local suppliers for scuba tanks and refills. 

You will need to weigh the costs on investment and upkeep of your own air compressor versus relying on a dive shop to fill your tanks for you. If you scuba dive frequently and know a lot of people who do, this may be a more worthwhile investment. For less frequent use or limited space to store the large piece of equipment, you may find $5 fill-ups more reasonable. 

Dangers to Avoid When Filling a Scuba Tank

Filling a scuba tank the right way not only includes instructions on how to do so but must also detail things you should try to avoid for the safest and successful fill-up. If your tank does not do its job during a dive, you put your life at great risk, especially in deeper water. 

Here are some key dangers to avoid when filling up your scuba tank: 

  • Over-pressurized tank: An over-pressurized tank puts a lot of strain on the tank and may cause the tank to wear out more easily over time. Watching the pressure gauge while filling is crucial to avoid these problems from occurring. 
  • Easy to fall over: Make sure you store the tank properly so no damage occurs or the tank bursts open if it comes in contact with something sharp. Tanks are tall and easy to knock over, so keep them secured and away from highly-traveled areas where something might bump into them. 
  • Careful with valve: Be gentle with your valve as turning it recklessly could break it. Make sure you make smooth turns of the valve and do not let them come in contact with other objects that could break them. You will want to close the valve snugly, but not too tight (which can lead to breaks). Open and close the value with semi-turns, as opposed to full rotations. 
  • Clean valve and tank: For the best upkeep and prevent unnecessary degradation of the tank, make sure you clean it after every dive. This will keep the surface area in better shape to keep the material in prime condition. 

Taking good care of your tanks is the best way to make the refill process simple and easy. Because the first steps are related to the inspection of your tanks, you can also do this while you clean it and take note of any damage that may have occurred while in the water or during transport. 

Filling a Scuba Tank the Right Way 

Filling a scuba tank is a straightforward process as long as you adhere to safety protocol, and you have the proper equipment. Filling a scuba tank yourself is entirely possible as long as you have a scuba-grade air compressor and filters to ensure that the tank has enough pressure, and the air is of high quality. 

If you don’t want to make an investment in the equipment, you can pay to have your tank filled at a dive shop, which will cost you around $5. The decision to fill your tank on your own or at a shop will come down to long-run costs and how frequently you scuba dive. In either case, the filling should be completed on tanks in good condition. 

Refilling a scuba tank is an important part of the activity, making it crucial that you do so safely so you can enjoy more time in the water. 


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Tim Conner, M.D.

Tim Conner, M.D. started boating in 1974. He has been involved in recreational boating continuously since then. Dr. Conner has been active in boating and watersports safety education for decades. He rode his first jet ski in 1997, and rejoined the personal watercraft arena in 2012 with a Sea-Doo GTX 155, followed by 2 supercharged SeaDoos. Scuba certification came in 1988, and he and the family have traveled the world snorkeling and scuba diving for decades. The family has recently taken up paddle boarding. Click the photo for a lot more.

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