This one too far gone for nano treatment.

Still need to hack, redo the waterproofing and then redo the tiles. If pipes, need to replace all the leaking pipes.

As for waterproofing, don't use those water based ones. Won't last long. Opt for bitumen based. Stinks but will last easily 10 years. And when applying, make sure at least 2 ft from floor to wall too. Applying multiple coats just to make sure.