The U1 front panel shows "No Water" and "Fresh Water" notifications in red(shown below), meaning there is no available filtered water to dispense.
Sometimes, an airlock phenomenon can occur with the new or fully drained water systems.
If you haven't already, please try the following to resolve an airlock:
Unplug the system from the electrical outlet.
Remove and reinstall all three filters accessible through the system's top one by one. Please see the U1 manual available here for instructions on filter removal/replacement on page 11.
Fill the supply tank's "Fresh Tap Water" compartment to the max line. IMPORTANT: Please fill the tank BEFORE placing it back onto the U1 system. Otherwise, the system will not filter the water if the tank was filled AFTER it was placed on the unit.
Plug the system back into the electrical outlet and turn the system back on.
Within about 7 minutes, there should be water available for dispensing. The first filtering cycle may produce less than 1/2 of a gallon of filtered water since the filters will take up some of the water to fill the internal volume.
Please contact us if the above does not resolve the issue for the next step.