Preheat oven to 180 C. Grease two 12-hole muffin tins or line with cases.
In a large bowl, stir together flour, bicarbonate of soda, sugar, salt and nutmeg. In a separate bowl, beat together pumpkin, eggs and water. Stir pumpkin mixture into flour mixture; beat until well blended. Fold in chocolate chips.
Bake in preheated oven for 30 minutes, until a skewer inserted into centre of a muffin comes out clean.