Of all the leak tests that you can perform on your pool a pressure test of the plumbing system is the most difficult to do but is easily the most conclusive of all of the leak tests. A pressure test, using either air pressure or water pressure, is the bread and butter of any swimming pool technician on a service call for a leaking pool.
How To Pressure Test A Pool
The process of pressure testing a pool involves isolating each part of the plumbing system in single lines of groups of lines. The system is then closed on one end, usually by plugging the return and suction fittings, and compressed air or water is inundated through the other. A pressure test of a pool plumbing system can be charged from 1 psi up to 30 psi. These are the normal operating pressures of a swimming pool filtration system.
Current plumbing standards, such as glued PVC pipe, can withstand hundreds of psi under normal conditions. New pool construction will sometimes pressure test systems up to 80 psi or more however this is extremely dangerous.
Pool Plumbing System Pressure
Even a few psi is enough for most pool leaks to be found. If you are going to try a pressure test you should aim for 5 psi of pressure and exercise extreme caution. Never perform a test, or work with with tools or machinery, that you are not familiar with safe working practices.
You close one side of each of the plumbing lines most commonly using rubber expansion plugs suitable for pressure testing. These are somewhat similar to winterization plugs which can be used with limited success for pressure testing at lower pressures except professional quality plugs are much more reliable and able to handle higher pressures safely. The two most common sizes of plugs are 1.5" and 2".
Pressure Test Tools
You can use house water supply pressures or compressed air from a portable compressor to charge the pool system. The one piece of the puzzle that is missing is the connection point, valve assembly and pressure gauge that together are a pool "pressure test tool".
A trip to any hardware store or plumbing store will provide you with all the tools and materials that you need to make a pressure tester. You will need to connect your air connection or water connection on one end and incorporate two valves for safe charging and discharging of the system. A good condition pressure gauge allows you to monitor any loss of pressure in the system which indicates a leak is present.
If you are thinking this sounds way over your head then you might want to consider bringing in an expert to quickly and safely pressure test the plumbing system for you.
Water Pressure vs Air Pressure Testing
When pressure testing a pool you can actually use either air pressure or water pressure to charge the system and the results are quite different. Air is compressible where water is not so a leak sounds completely different depending on which you are doing.
There is no right answer as to which is better as leak detection professionals use either or both of these methods. The method that you use will depend on what tools you have. Using water to pressure test the pool system is probably the safer and easier method to use.
Pressure Testing Pool Leaks
Most of the time adding pressure to a pool pipe will only tell you which line is leaking. A pressure test can help you take this one step further sometimes as the use of listening devices, such as a stethoscope, can assist you with pin pointing the leak location.
Even toy grade stethoscopes can sometimes work well enough to pinpoint pool leaks under pressure and it really depends on the size of the leak and the medium of backfill that was used to bury the pool pipes.