Check Valve Needed?

I have a basement bathroom that requires a pit and ejector pump to move the waste up to the septic line. The check valve makes a loud bang when it closes, and I've been thinking about replacing it with a different model that hopefully wouldn't bang so bad.

However, in looking at the plumbing I'm not sure why the check valve is there. After the check valve, the pvc continues vertical to a point that is about 8-10 inches higher than the septic drain line, then joins the the septic drain at a 45 degree angle. It seems to me that with the ejector piping being actually higher than the septic drain line, there is no chance of sewage having a reverse flow into the ejector line. Why is the check valve needed?

Any comments on this would be greatly appreciated.

mark

Yes the check valve is needed. This keeps what has been pumped out of the pit from flowing back down the pipe and back into the pit once the pump shuts off. The ejector pit piping is supposed to go vertical past the piping it dumps into as you've described.

valve

Without the check valve, if the main line ever fills with water, which can happen during rainy seasons with a septic tank, the pump will suck water out of the pipe every time it shuts off and then have to pump it out again in a continuous on/off/on/off cycle

Thanks to both RioHyde and HJ for the replies, and I will definately use the check valve, based on your recommendations.

Mark