Paul Franklin wrote:

The water won't be bearing on the pump, it will be bearing on the
check valve. You need a check valve above the pump or the water will
just drain backwards through the pump into the sump when the pump
shuts off. Spend a few extra bucks for high quality check valve and
you're done. I prefer the PVC type that are combo checkvalves and ball
valves so you can fuss with the pump without all the water pouring out
of the pipe.

Now if you're worried it might freeze, that's a different matter, but
as long as you can slope the short length that goes through the sill
so it drains, it should be fine unless your basement or crawl space
gets really cold.

HTH,

Paul

Thanks. My system does have a check valve. I don't mind there being 5 or 6
feet of water in the vertical pipe above the check valve. I just don't want
another 25 feet of horizontal pipe full of water also being above the check
valve. So, my plan is designed to prevent that from happening.