If your sink can handle whatever food you want to grind up in a disposal unit, it can surely handle ground coffee, I reckon. I'd be afraid of clogging up my sink.
I thought so too but we had a clog about 6 months after moving into our last spot. Plumber said it was due to flushing the grounds down the sink. We stopped doing it and it didn't clog until we moved out a year and a half later. Could have bought a lot of filters for the price of the plumbing bill, probably would have come out even on K cups tho
I stand corrected - good to know. http://www.atomicplumbing.com/plumbing-news/is-it-safe-to-dump-coffee-grounds-down-the-sink/
Unfortunately, this isn't true. While coffee grounds down the drain may seem harmless, they're actually very problematic and are the source of a lot of clogging issues.