peggie just purchased a 74 ericson 35 II. the sanitation system aboard is a kracor retention system. this system doesn't appeal to me for obvious reasons. there is a 1 1/4 inch thru hull for pumping out the 6 gallon holding tank. i plan on replumbing the system to a conventional system. the only problem i have is getting water to the head for flushing. in the head i have a 3/4" thru hull for the sink drain. this thru hull is below the water line. i was thinking about teeing off this thru hull for the rinse water for the head. when flushing the head will the pump pull water thru the thru hull or will it pull the water out of the drain hose and then suck air into the system ?? also if i wanted to pump the head directly over board i would need 2 y valves. one between the hand pump and the thru hull and 1 between the toilet and the holding tank. there are no other thru hulls available to draw water from. peggie any and all help would be greatly appreciated thanks greg