Preheat oven to 180 degrees C (350 degrees F)
Melt the butter
Combine the oats and melted butter in a bowl
Add the sugar, raisins and flour and mix. Mix in the water. The batter should be firm
Make small balls of cookie mixture and flatten them on a baking tray lined with baking paper
Bake in the centre of the oven for 12 minutes - cook longer for a crunchy cookie
Let cool on a rack; serve