I have a frost free water valve typically used for farm use.
Open the valve and the water is available, torn off the valve and the water source is closed 4 ft below grade and water in the valve drains out, no water above grade.
I want to run this to a sink and to a toilet, but need to have no water remain in fixtures.
For the sink I am using a straight facet (not angled up) which would drain when water is shut off, sink would have no trap.
For toilet, I don't want a water tank and a trap. I want to just open a valve and flush out the toilet leaving no water behind.
This is to be used in a storage building at the back of my property.
The water comes from a 2400 gallon cistern in the ground, fed from the roof (steel) along eves troves to down-spout thru a debris filter into the holding tank with an overflow to a dry well.
I am planning to use solar heating to in-floor heating. The building will be below freezing some days and nights.
Once upon a time you could get a toilet with a straight opening and no trap.
Toronto, Ontario, Canada
A toilet that has no tank is possible if the water supply is large enough. These are usually found in large commercial buildings. Even if you have the supply, there will be water in the bowl and, there's no way you can not have a trap.