Water can be made by

1)Making a sector with a lotag of 1.  This is the water's surface.

2)Make a seperate White! sector the exact! same size with a lotag of 2.

3)Put a sector effector with a lotag of 7 and an original hitag on the surface
  of the water.

4)Put an exact copy of that sector effector in the exact sameplace in the
  other sector.

5)Make sure both SEs are on the floor by aiming at them and pressing ctrl+pgdn

6)Assign textures accordingly.
