Not sure if, two days later, you've resolved problem.... but we had this problem earlier this year with our two GOS weaners.... After much research (TAS included) it seems that pigs' natural inclination, upon the shock, is to run forwards (out of penned area), so some time is well spent training pigs to run backwards, away from the wire, and so staying in their penned area.... We have a similar set up to yours, ie wire encloses a good area, but that area is within a larger fenced field, so not the end of the world if they break free. But still, it's a nuisance...
We went to the bother of putting some hurdles around their ark, making a small pen, about 4 large hurdles each side, and set up an electrified tape just inside. This gave them a visual cue, and also meant that when shocked they could only go backwards, away from the wire. Kept this in place for two days. Felt very sorry for pigs having limited space for those two days, but it was still better than the stable they'd left, and better long term. Once the hurdles (and inner tape) removed, they barely challenged the wire, with occasional squeals, and both of them always running backwards.... Would never do it differently now...
Water treatment sounds a bit harsh.... good luck