Will Toto Drake/septic work with no grey water in toilet line to add water?

Thinking about a Toto Drake. It would go on the 2nd floor of my house so there's a 2 story drop from the toilet down the line to the ground and then about 15 feet to a 90 degree turn and another 35 feet or so to the septic tank, gradually downhill all the way. I'm wondering if a 6 litre flush as in the Toto Drake be enough to move things along. Naturally there would be other flushes in between with just urine. My grey water is separate from the septic tank so there would be no extra water going through from washing, etc.

Thanks for your input.

Richard

They work just fine for that.

Many folks do not understand that poop does not make it to the sewer or septic tank with the first flush. This is normal, so don't worry about it.

Thanks for the quick replies. I didn't think it made it there on the first flush, but as long as it eventually gets there on just toilet flushes and no grey water, I'm happy. If you guys are confident, I'm confident.

If it didn't what would be your alternatives?

Flushing more often to add more water is about the only one I can think of. With the old toilet I'm putting through seven gallons per flush vs only 1.6 with the Toto.

The old bowls flushed so slowly that there wasn't really a surge. A toilet easily move waste 50 plus feet on the horizontal.
My parents home went 250 to the public sewer. It's never been a problem. It has two bowls of 1.6 gallons and one old 3.5

Was their grey water separate as well or do you think that's not much of a consideration in the horizontal movement of waste?