Although propane companies have specialized equipment designed for checking for leaks and their severity, consumers can check for leaks themselves. The process is quite simple while the supplies and ingredients are found in almost every home and consist of just soap and water. Using a solution such as this is safe and will not harm a propane tank or plumbing connections. It's been heard of that people use a match or lighter to check for leaks and nothing could be more unsafe. Soap and water will safely identify and give an indication of the size of the leak.
Homemade propane leak detector solution can be placed in a spray bottle or other container. Liquid dishwashing soap will produce the most bubbles when mixed with water and is what's most commonly used. If a spray bottle is used, adjust the tip of the sprayer so that a sharp stream is produced by squeezing the bottle's trigger. Don't use a broad misting as this won't adequately cover the connection or seal that's being checked for leaks. The sharp stream will provide enough of the soapy mixture to produce bubbles if there is in fact a leak as well as reaching into any recessed connections that are not easily reached. Using a sponge or dish rag to dispense the solution will adequately indicate any propane leaks as well. A leak such as the one to the left (with the red regulator) may result in the loss of one gallon of propane over a years time. The propane gauge leak at the bottom left may result in the loss of one gallon of propane over 3 years. These leaks are common on older tanks and installations so do not be alarmed if you find a leak.
As a general rule, small bubbles indicate a small leak while large bubbles indicate a larger leak. Tightening the screws on the face gauge (pictured left) would probably stop this leak, or any leak around the face gauge. However, trying to fix the leak yourself may do more harm than good. This is especially true on older tanks where the screws may be easily sheared off if over-tightened. The best thing to do is call your propane company and let them know that you've found a leak and they'll make arrangements to take care of it. Again, small leaks like those pictured here are not cause for alarm so don't worry about the amount of gas coming out of the tank or the amount of gas you're losing. It's not all that much and leaks of this size are easily fixed by tightening a fitting or connection.
See Gallons of Propane Lost in LP Gas Leaks for additional information.