In a large saucepan, combine water, sugar, flour, salt, vanilla, butter or margarine, and lemon juice. Mix well, then stir in raisins. Simmer over low heat for 10 minutes, stirring frequently. Remove from heat.
Pour raisin mixture into pastry-lined pie pan. Cover with second pastry. Seal edges and cut steam vents in top.
Bake in preheated oven for 15 minutes, then lower the heat to 350 degrees F (175 degrees C) and bake an additional 25 to 30 minutes.