The water module is only available for a range of crops in the tool:
Alfalfa, Barley, Coffee, Cotton, Dry Bean, Maize, Millet, Oats, Other grain, Other legume, Other N-fixing forage, Other Non-N-fixing forage, Peanut, Perennial grass, Potato, Rice, Rye, Sorghum, Soyabean, Spring wheat, Tomato, Vegetable, Winter wheat
It is not available for the following:
Apple, Canola, Clover, Grass-clover mix, Hops, Rapeseed, Tea, Tree Crop, Blueberry, Raspberry, Strawberry, Other, Other root crops, Other tuber crop
Therefore you can only make a combined GHG & Water assessments for which the water metric has been developed. If you want to assess another crop, start again and only select the GHG metric.