FBO Self Serve not being checked for a month.

[pfarber]

Every 2-3 days seems adequate to me.

Routine checks are the only time we check airline tanks and that's only done once every 7 days.... and that's if the MX actually does the check. The possibility that the check valve doesn't close (MX accidentally twists the sump locking it open LOL) is never zero.

I've sumped hundreds of tanks and never, ever found water.

Also the standpipe in a fixed fuel tank is several inches above the bottom. You'd need dozens of gallons of settled out water before it got to the pump inlet.