Piezolines (and pore pressure grids) only affect the pore pressure. They do not increase the weight of the elements that lie below them due to saturation and they do not add weight if they lie above the surface of the model (ponded water).
The weight of the water must be added separately. This is done by defining a saturated unit weight and by using ponded water loads when the phreatic surface is above ground level. See Tutorial 7 (page 7) for how to apply a ponded water load.