Here's what you need to understand.
The car's cooling circuit should ideally seal. i.e once it is filled with water / coolant you should forget about it.
If the car is loosing water, that should point you to find out where the water is going !
a. Like you pressurize the AC cooling circuit and then wait for 30 mins or so to check for pressure drop; same needs to be done with water system; except you need to wait more than 1 hour. If the pressure drops then there is a leak some where which you need to find.
Since you have checked the hoses, you need to pay attention to radiator find for a small leak.
b. check if water is mixing with oil; you need to check for frothy oil, or water with traces of oil in it. In this case you need to fix the gasket and have the head refaced again.
enjoy !