Date filling: Place water and dates in saucepan. Cover and cook on low heat for 15 minutes, stirring occasionally, until the filling is thickened and smooth. If the cooking mixture is too thick, add a little water.
Stir in the lemon juice. Set aside.
Mix flour, oats, brown sugar and baking soda.
Cut in butter until mixture is crumbly.
Press half of the crumbs into a greased 9 x 13 pan.
Top with Date filling mixture. Spread evenly with a spatula.