On Mon, 05 Nov 2012 20:40:55 -0700, Robert Neville wrote:

Yes, you are missing something obvious. If there is no check valve
there, water can be drawn by vacuum back into the house. The elevation
of the line is immaterial.

Hmmm... that must be true because they bothered to put the check valve
there.

Are you saying ALL houses which have a separate line for garden hoses
than for the house, have a check valve ONLY on the garden hose line but
not for the house?

Because I have only one check valve ... and it's ONLY for the garden
hoses.

The way I know that is I shut it off (because it was leaking), and only
the garden hoses stopped working.

So, is EVERYBODY's house designed this way?