On Jul 9, 6:08*pm, "Ultraglide"
wrote:
I had a back-flow preventer installed last fall. *It works fine but I have a
question. *There is usually about 1 inch of water inside the housing. *When
I open up the inspection cover, it drains away but more enters after a short
while. *My question is this: *Is this normal? *If not what do I do to
resolve the problem.

Doesn't sound like a problem tome.