Water bubbles on sidewall of vinyl liner

I have 4 vinyl liner pools we take care of that get a water bubble behind the liner on the sidewall. We pull the liner back and run our hand up the wall and work the water out. Maybe amounts to 1 1/2 to 2 gallon of water. A couple of months go by or even into the following year and another one will show up somewhere else on the pool wall. Have checked the pools for leaks and nothing. Losing no water besides evaporation. It is not ground water buildup because the liners are not floated, and we installed sump pits with drainage around the pools when they were built and the pits will be completely dry. The pools are galvanized steel panels with 1/4 inch wall foam between the liner and panels. Out of ideas on what is causing it. Anybody seen anything like it?

Replies

John T. Salvo September 21, 2011 at 5:19am

We have seen this quite a few times. Typically it is from water seepage under the decking to the pool wall. Another more common cause is the pool getting overfilled and the water is then getting behind the liner through the liner track.
David Jamieson September 7, 2011 at 12:20pm

This is a common problem in vinyl liner kit pools with poor drainage. If there is no leak in the liner in the area of the bubble the problem is always surface water or over flow. I know installers that caulk between the joints when installing the pool. a good quality duct tape helps. Next time you remove the liner to get the water out, try a squeegee on the out side of the liner to move the water up the wall.
Brian Embry August 26, 2011 at 6:44pm

I've seen this situation a few times, and it turned out to be gaps in the coping allowing rain/sprinkler water down behind the liner. Solved it by sealing up the coping witha crack sealer(sakrete).
Nathan Edwards April 1, 2011 at 3:02am

Will let you know. Last summer only had one of them that did it not all four. I will pay attention to surface water, and test the water behind the liner if any do that this year. Hopefully will be able to determine what is happening.

John MacTaggart said:

I've only seen the issue you are describing twice. Once was on a friends pool with watershears and when they would first start up the water would run down the front of the planters they were installed in and would gradually work it's way behind the liner and get trapped on the side wall in the pockets of the wall foam (it would take 4 - 6 months for a slight bubble to become visible). The only other time I saw it was on a job site with a builder I sell to and the pool had perimeter fiber-optics on it. I think he ultimately determined water was getting behind the liner/wall foam b/c the hole where the f/o cable ran back from the liner track to the light source wasn't sealed. I think he ultimately came to the conclusion that the gap was allowing water to leak behind the liner, sealed it and the problem went away. Other than that you got me stumped, but Lester's suggestion is a great one. At least then you'll know if the water is coming from the pool or not. The way the wall foam adhesive is laced when you spray it onto the wall forms all kinds of pockets where water from any source that gets behind the liner can run into and get trapped. If you get to the bottom of it please let me know what the actual solution is. I'd like to know in case I ever have a dealer that runs into a similar situation.

Thanks,

John
Scott Tarr March 31, 2011 at 8:02pm

Great idea Lester on testing the water behind the liner...what a quick and effective way to see if the source of the problem is coming from the pool.
John MacTaggart March 31, 2011 at 6:40pm

I've only seen the issue you are describing twice. Once was on a friends pool with watershears and when they would first start up the water would run down the front of the planters they were installed in and would gradually work it's way behind the liner and get trapped on the side wall in the pockets of the wall foam (it would take 4 - 6 months for a slight bubble to become visible). The only other time I saw it was on a job site with a builder I sell to and the pool had perimeter fiber-optics on it. I think he ultimately determined water was getting behind the liner/wall foam b/c the hole where the f/o cable ran back from the liner track to the light source wasn't sealed. I think he ultimately came to the conclusion that the gap was allowing water to leak behind the liner, sealed it and the problem went away. Other than that you got me stumped, but Lester's suggestion is a great one. At least then you'll know if the water is coming from the pool or not. The way the wall foam adhesive is laced when you spray it onto the wall forms all kinds of pockets where water from any source that gets behind the liner can run into and get trapped. If you get to the bottom of it please let me know what the actual solution is. I'd like to know in case I ever have a dealer that runs into a similar situation.

Thanks,

John
Lester Eric Brehm March 31, 2011 at 1:03pm

Test the water from behind the liner for pool chemicals , CYA is what I would look for, if it is being used in the pool.That should give you a direction to go from there.
Steve Wiencek March 31, 2011 at 9:55am

There are only three sources of water that can go behind a vinyl liner:

1) Pool water

2) Groundwater

3) Surface water

If you have eliminated the possibility of a liner/plumbing leak and groundwater, this only leaves the possibility of surface water, i.e. rain, sprinkler, or runoff. What typically happens in cases like this when the ground becomes saturated (think wet sponge) and cannot absorb anymore or percolate downward, the water lays and goes through the seams of the steel panels behind the liner as a result of the surrounding hydrostatic pressure.

Look for any kind of relationship between when it occurs and times of surface water accumulation.
Nathan Edwards March 31, 2011 at 2:40am

No water features on any of them.

John MacTaggart said:

Do any of the 4 pools have a water feature that spills into the pool? Like a spill-over spa, water-shear, etc...?
John MacTaggart March 30, 2011 at 11:30pm

Do any of the 4 pools have a water feature that spills into the pool? Like a spill-over spa, water-shear, etc...?