Sump pump check valve
The best place is down by the pump. If you have it a long way away, then every time it pumps out, there'll be a lot of effluent flowing back from where the check valve is into the basin again afterthe pump shuts off. It's not going to hurt anything, but you'll get a more complete "evacuation" if the check valve is closer to the pump.
The other possibility is that the pipe will hold a vacuum along that whole length up to the check valve (like holding your thumb over the end of a straw). In that case, your pump is going to have to overcome some excess resistance to pump out each time - could shorten the life of the pump.
Last edited by Ishmael; 01-25-2010 at 06:46 PM.