It's been a little more than two and a half years since I set up an experimental drain for my plumbed-in Rancilio S26 (commercial espresso machine), and I can report that it's working out well.

Background: There's no convenient drain in the corner of the kitchen where I wanted my machine and grinder set up. After thinking about it for a while, I decided I'd try a condensate pump (such as one uses with a condensing furnace or central air conditioner) and a branch tailpiece drain line adaptor in the sink, of the type that is used to accommodate the discharge from a RO drinking water system without making getting rid of the port which the dishwasher hooks up to.

Long story short, it works great. I brought fresh water over to the machine with 3/8" polyethylene tubing, then put a second run in parallel back along the baseboard. Some gymnastics were required to adapt the output of the condensate pump to a push-in connector, but you can find all the bits you need at Home Depot or Lowes.

It seems that every four to six months ago the pump sounds slightly funny when it cycles and I have to pull out the wine fridge and clean out accumulated coffee sediment from the sump of the condensate pump (which honestly was expected). Oh yeah, I put a sign on the tray that says "no milk!" since I don't want something disgusting growing in the pump.

Bill of materials:

Condensate pump

Drain line adaptor

Angle stop valve for cold water to machine