Hello~
Are you feeding just endive? Just FYI there is a very good list of veggies to feed at Beautifuldragons.com you want to switch it up a bit because feeding the same thing ALL the time not only can get boring, but feedign verious things will insure proper nutrition.
Water poo can be a number of things. The water that is not absorbed and turn into urates (the white part) will come out as excess water in the poo. This is normal as long as the poo is some what solid and formed. However, if the poo itself is not firm and runny there could be problems. Checking your temps with a proper digital prop thermometer is advised. Let me know what they are.
Is she/he pooing every day?