Would the three foot high toilet in your test not hold water as pictured, because the trap is located under the water supply. Thus the water would seek a lower level even with the low side of the high end of the trap?
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
The trap is below the water supply, static pressure would force the water down to seek the level of the trap.