Well, I have played around a little more with a "mock-up" graywater system.
I had a 30 gallon barrel in my laundry room, which the output from the washer goes to.
In the barrel, I dropped in a submersible "power-head" pump from an aquarium, connected to a garden hose. A powerhead is the exact size to fit into the cut-tube-end of a garden hose in case you were ever wondering.
The other end of the hose went right into the top of the toilet (with the lid removed), held in place by an Eco-Clamp. (Green-handled spring-clamp)
The pump was connected to wall power through a remote on/off switch, sold as an easy way to turn your X-mas lights on and off in the winter.
So:
Use the toilet.
Flush.
Press the button to turn on the pump.
Watch the toilet tank fill up with graywater.
Press the button to turn off the pump.
Go do something else until you have to use the toilet again, then come back and repeat.
After looking at how a typical well-fed plumbing system works. I think I will do something similar.
Have a pump that turns on and off with a pressure switch. Use a small pressure tank. The pressure tank will feed water to the toilet, and the pump will automatically turn on and off only as needed. I think I just need a check valve in there somewhere!
This is very similar to how the power brakes on my electric car work!
Can anyone tell me what the difference between a Pressure Tank and a Thermal Expansion Tank is? I can get a 2-gallon Thermal Expansion tank for $5! Sounds like a pressure tank to me!