Need to glue/bond two pieces of relatively thick vinyl.?

Question

Was gifted a new backpack which contains a removable vinyl "bladder" that you can fill with liquid and use for drinking from an attached tube. Problem is that the "bladder", which is made from a fairly thick vinyl material heat-fused around the circumference leaks from a small area (perhaps 1/2" long) of that seam where the fusing did not "take".

Is there a glue or similar material that will repair this defect? The area is easily accessible to apply the glue and clamp together for whatever time it would take for the glue to dry/cure. I'm asking this because I've had many poor experiences trying to patch inflatable vinyl toys and air mattresses. Hoping there's something magic out there you will know of.

Answer 1

you might try a SCUBA equipment store. wetsuit patch/glue.

Answer 2

Take it to a swimming pool shop and see if they will fix it for you.  They have to seal above ground pool liners all the time.

Answer 3

SOOPA GLOO