Combine spinach and water in a saucepan. Cover, and cook till spinach is very tender. Cool slightly.
Place spinach and liquid in a blender along with the egg and salt. Blend till smooth. Transfer to a bowl. Add enough flour to make a stiff dough.
Turn dough out onto a lightly floured surface. Knead for 1 minute. Roll very thin on a floured surface. Let rest 20 minutes. Roll up loosely. Slice .5cm (1/4 in) wide. Unroll. Cut into desired lengths. Spread out on a rack to dry for 2 hours.
Fresh pasta needs only a few minutes in boiling water and it's done. It is finished cooking when the pasta rises to the surface.