Long-necked, flying white bird grazes water with black legs.
A bird drinking water from a swimming pool.
A bird grazing water is not always drinking it.  A bird can graze water from other things besides a swimming pool.
exists e1 e2 s1 s2 x1 x2 x3.(r_long-necked(e2) & with(e2,x3) & n_leg(x3) & a_black(s2) & Theme(s2,x3) & Theme(e2,x2) & Actor(e2,x1) & v_graze(e2) & n_water(x2) & n_bird(x1) & a_white(s1) & Theme(s1,x1) & Actor(e1,x1) & v_fly(e1))
exists x1 x2 x3 x4 x5.(a_topic(x1) & from(x1,x4) & n_pool(x4) & of(x4,x5) & n_swimming(x5) & n_water(x1) & of(x1,x3) & n_drinking(x3) & of(x1,x2) & n_bird(x2))