Possible Leak - Localized Water Behind Liner

[smthomas7]

My pool is about 1-1/2 years old. I have never had any issues till now...thanks to following the advice on this site for general pool care/chemistry. Just today I noticed a relatively small bubble in the liner at the water line. I know it wasn't there a couple days ago as I cleaned the waterline. The bubble is about 1-2 feet wide and extends from near the waterline down the wall about 18". It also extends an additional 3-4 feet along the waterline, but only goes down about 4-5 inches Below the water level. The bubble does not stick out very far, so it is hard to see until you get close to it. Also, the bubble seems to have a very distint edge and no evidence of the liner being soft even a few inches away in any direc tion.

I am trying to figure out the cause. The water level hasn't changed (at least not yet). I have never noticed the issue previously even with large amounts of rain despite having clay soil and a flat yard. And it hasn't rained that much in the last week, so I can't imagine I suddenly developed a ground water problem. I have not pulled the liner off the track to test the water (salt pool so I should detect salt if from the pool)

I looked in the general vicinity of the bubble and didn't see any obvious punctures or tears in the liner. Confused about where I should be looking. Would the leak be near where where the bubble is located? Or, could it be coming from further away and following the water line or coming up from a leak on the bottom? I intend to get some food coloring to look for leaks more closely, but I assume this be difficult to find if it a slow leak.

Thanks for any advice/guidance that anyone can provide.

 

[gwegan]

How high is your water table?

I suspect the pool is not the source of the bubble.

Do you have drains or dry wells nearby to dewater the area.

A leak often causes no bubble it just leaks. If the water table ( or something else) wasn't there the bubble would just dissolve down below the pool.

 

[smthomas7]

How high is your water table?

I suspect the pool is not the source of the bubble.

Do you have drains or dry wells nearby to dewater the area.

A leak often causes no bubble it just leaks. If the water table ( or something else) wasn't there the bubble would just dissolve down below the pool.

I don't have any drains or dry wells near the pool area. However, the pool is slightly raised...the yard was graded so that the pool deck is even with the back porch. This places the waterline slightly above the yard level on each end of the pool (ground slopes down away from pool on each end). This is why I am suprised there could be any water behind the liner (leak or water table) at the waterline.

I am just suprised I would now have a groundwater problem when there have been much more wetter periods in the past year than we have had in the last couple weeks. I also thought a high water table would cause other parts of the liner to push away. Also, nothing has changed in regards to drainage on the rest of the property (for example no downspouts entering the vicinity of the pool.)

 

[smthomas7]

Could it be a localized leak that is not carried away fast enough to prevent the localized bubble? Maybe it is draining away, but not fast enough since the water pressure below is keeping the liner tight to the wall. And I don't know if the joints in the steel wall panels are possibly sealed and not allowing water to drain through the joint.

I am thinking I may need to first pull the liner bead and test the water behind the liner for salt to determine if salt is present. If so, then I need to look further for a leak. Just trying to narrow down where I would even start to look. This seems pretty daunting if it is small leak.