All my pipes are hidden, in the walls or under the floor, as there was no sign of dampness in the house, we opted for lifting the tiles and concrete under the kitchen floor. We soon found damp in the sand, so just cleared the sand to show the pipe until we found the pinhole. No special tools, just graft and hope for the best....
Re-concrete and tile, sadly not that long after, had to do the same again.
But it has been OK now for about 14 years, just the loo flaps and the odd tap leak....