I thought they were. Figured something quick and removable was possible for sink. But, have you or anyone you built this tank & plumbing setup for, camped successfully in below freezing temps? How cold would you estimate your setup would be safe for? Does the forced air furnace you you use also run on 12v for traveling in the cold? Since running a propane appliance while trailer is moving is not recommended, and dangerous during vehicle fuel refilling.the water and all lines are in the unit, but when you need the sink cause it is on the outside of the unit, I use quick connect hose's to go from the trailer to the sink........