car require about a gallon of water after being driven for about 50 miles why?

the jug is where I put water in until I find out what's causing the car to use so much water with no leaks visible the water should return to the jug ,the overflow is the jug,it should be a rotation from the jug to the radiator through the ports and then return like recycling back to the radiator then back inside the jug that's on the firewall.Maybe I should remove the thermostat it's not running hot I add water when the inside gauge light comes on

Whatever you think, I'm not there and can't check it for you. Good luck

Okay that's understandable,now this jug that you're where suggesting should be pressure tested where is it located I'm thinking that one belt(could be slipping) should be tested maybe it's a matter of adjustment Thanks