Coffee Grinds down the drain or no?

[pacanis]

Absolutely NOT. PERIOD..........................
My dad's a plumber.
No coffee grounds.
No cigarettes [yes, people really DO put them in there].
No glass to sharpen blades. Ice is fine.
No egg shells.
No potato peels.
No bacon drippings or other fat, unless you follow it up with a truckload of HOT water but even that isn't full proof, it can still harden later and clog big time.
No animal bones.
Lemon/lime/orange peel is okay in small pieces to help deodorize.
yes, he's found them all and they all clogged and broke the GD.

Geez! Is hard water OK?