check valve on mainline gravity?

[FunnyFarm]

Should one have a check valve on the mainline at the bulk tank on a gravity line?

[ennismaple]

No - it'll freeze and block the line and will be somewhere for crud to build up. Even if you have natural vacuum on your lateral lines the mainline is free flowing and isn't under vacuum.

[jmayerl]

A check valve would be of no benefit.

[FunnyFarm]

thanks wasn't sure