When cleaning up my Europiccola Millennium in the morning, post-capp, I generally leave the machine and parts as sparkling as possible. And empty.

For awhile, my last step was to fill up the machine, so that it'd be ready to go for more espresso later in the afternoon, or more likely, for the following morning's cappuccino.

But then, those around me started wondering about possible corrosion of the machine and/or health issues related to the practice, so I stopped. It may not sound like a big deal, time-wise, but somehow having the machine locked and loaded (sans coffee, of course) in the morning seemed to make a big difference.

Walk into the kitchen, turn the machine on, and immediately start focusing on grinding. Bliss.

What do you think?

leave water in it. It does absolutely no harm to the machine.

Here's a simple test: Allow the machine to come to pressure, draw water through the group into a cup. Open the steam valve to depressurize, empty and then refill the boiler with fresh water. Allow the machine to come to pressure, draw water through the group into another cup. Allow both cups to reach room temperature for a couple hours and then taste. Can you tell the difference between the samples?

That won't tell you if there's leeched metal concentrates, but at least you'll know if it matters taste-wise. The thread Can water go stale? discusses a similar test with the Expobar Brewtus. Mark reported all the water samples tasted off:

Dogshot wrote:1) Water that had been pulled from a clean machine that had been well flushed and with fresh water in the reservoir and allowed to cool to room temperature tasted off;

2) Water that had sat in the boiler over night, pulled, and then allowed to cool to room temperature tasted off;

3) Water that was heated in a ceramic mug in the microwave almost to boiling point and allowed to cool to room temperature tasted off (try it!).

The only water that tasted bad was water that sat for 24hrs in the reservoir, and was tasted at room temperature without passing through the espresso machine at all.

Good question.
I probably empty the boiler of my Gaggia Factory once or twice a week. Using it a few times a day keeps fresh water coming into and out of it. I've had no problems in the ten months I've had it.

pavman wrote:But then, those around me started wondering about possible... ...health issues related to the practice,
Walk into the kitchen, turn the machine on, and immediately start focusing on grinding. Bliss.

First, tell them that you sterilize the inside of the machine and the water every use... ; >
And second, how long does it take you to grind that you have to focus on it for thirty minutes? You are letting the machine reach some sort of thermally stable temp before making shots, yeah? How long between switch going on and the first shots? I wait at least thirty minutes with the Factory, but that's cause I follow the same morning routine as I do for the Silvia. Could I be getting my morning shots quicker?