A Craft Beer & Brewing Magazine reader recently asked us the following question:
I assembled a new keg system, and it has a slow leak as it drained my entire CO2 tank. How can I find the leak?
It can be quite maddening to assemble a new keg system only to have your CO2 tank empty out over a period of days or weeks. Even a small leak can cause CO2 loss over time, eventually draining your tank. Here are a few of the steps I take when setting up a new keg system. First, I carefully check all of the connections to make sure the hose clamps are tight and seal well. It is not uncommon for new keg connectors or taps to be a bit loose. For the kegs themselves, I prefer to use a bit of keg lube on the posts. Keg lube, which you can purchase from your homebrew store, is a food-safe lubricant that provides a nice seal in the event your keg connectors are not a perfect seal. It is not a bad idea to check the rubber keg seals and seals on the keg posts as well as the poppet valves on the keg posts to make sure these are in good condition, as a leak on the output side can create quite a mess as beer pours from your pressurized keg. Next I perform a leak check. To do this, I prefer using a large glass container, such as a clear bowl. Put water in the bowl and then very gently add some dish soap or, alternately, mix in some Star San. Soap works well, but it needs to be rinsed well because soap can reduce head retention in beer. Star San works well because it will foam when the CO2 bubbles through it but does not need to be rinsed. Put the system under pressure and then check each of the keg connectors by immersing it in your bowl and watching for bubbles. Do the same with as many of the other connectors as you can reasonably immerse. If you have connections that can’t be immersed, you can spray or drip some water or Star San onto the seals and look for bubbling. Another trick is to disconnect your beer kegs and up the pressure on the system to roughly twice the normal operating pressure and check again for leaks. Often you will find leaks at the higher pressure that might be hard to detect at low pressure. Remember to turn the pressure down again and bleed off the excess CO2 before connecting your kegs again. This is the best method I have found for isolating leaks.
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