Trying to find leak in inground pool

[Annorax]

Hello all,

I have a vinyl lined, DE filtered, inground pool that is probably at least a decade old (not sure of exact age or volume).

Since last year, one of the return jets has been blowing some sand into the pool and this year, I've noticed that the water has been draining somewhat fast (maybe an inch or so per day). I don't see any visible leaks in the liner so I've manually plugged the 3 return jets (including the one blowing sand) to see if that stops or slows it. The water is already below the skimmer basket that is not the problem.

I'm still waiting to see if plugging the return jets stops the leak but I have a few questions.

1.) I have 3 total return jets and the one the farthest from the filter is the one leaking sand. My hunch is that this is the one with the leak. Could I leave just this 1 jet covered and still run the filter or will pressure build up and cause further damage?

2.) If the leak is in an underground return pipe, will I (either myself or hire someone) have to dig up the ground and break stone to fix the pipe? There is about a 3 feet wide area of stone around the entire pool and beyond that is grass - I'm hoping they could just dig underneath the stone if they had to? If not, how else could this be fixed?

 

[Texas Splash]

A potential leak underground can be a mess and a bit difficult. My first observation though is to be sure where that leak is. Even though you suspect it to be around the return side, it puzzles me because when you have a pressure side leak (from the filter back to the pool), water is under pressure pushing "outward" from the pipe. It generally is not able to suck dirt into the opening while running. Also, with a pressure-side leak, you would expect the ground to be wet/soggy. So how would dirt get into the lines? Maybe from the suction side, from the main drain/skimmer(s) to the equipment pad. I wanted to mention that just in case you wanted to consider investigating the potential leak a little more before digging.

If you do find a leak underground and under concrete, then it all boils-down to equipment, DIY skills, and time to repair. Some people might cut-out some concrete to same time and avoid tunneling-under the decking. Some might just dig to find the suspect area. Others say none of the above and just call a leak detention company to pinpoint the area and possibly repair it as well.

But I would be sure of the suspect area before going too much further. Remember you can also turn-off your system, isolate the pressure side by closing-off valves, and let the pool sit overnight to see if water leaks from the pool structure or suction side. So a little creative manipulating might help you diagnose the problem as well.