What the heck could that be? One day after a perfectly clean mushroom. Weird.

yikes.

Copper salts, probably somehow from brass and somehow related to the soaking. I'd clean(scrape, scotch brite) it off, flush the machine w/ water several times and recheck. Anyone with a better idea why this happened?

Marvin

Wow, that was some weird alien parasite type stuff growing there...

Did you ever get rid of the taste?

whoa. that's impressively green.

Looks like mostly copper carbonate. Your mushroom has "patina." To really make a fair taste comparison, you at least need to compare boiler water to water drawn from your supply and raised to boiler temperature and held there for a roughly equal length of time (in stainless steel). Unless water has a large amount of volatile contaminants to begin with, boiling makes it taste crappier, because dissolved air is driven out.

I was curious about the taste because my machine I believe has a stainless steel boiler (Saeco Via Veneto,plastic version, with non pressurized portafilter) and I tasted the water brewed from it and compared it to boiled water from a stainless steel pot and a cheap supposedly stainless steel kettle.

The worst water was from my espresso machine it had a weird alkaline-y taste, sort of like baking soda.
The kettle had a bit of a plasticy taste, and the pot water tasted a bit funny but the best of the 3.
I did a descaling a few months ago with Dezcal, I should have tasted it before (I wonder if it was better or worse).

I'm planning on getting a QuickMill Silvano (with copper boiler) ill taste test it when I get it, and hopefully it doesn't start tasting funky as well.

*update* I did get the QuickMill Silvano machine and water through it does taste better, pretty much like boiled water from a pot. (Although steam wand steam has a bit of a funny smell to it, probably because it's new.). Hopefully the water out of it will continue to be decent tasting. I have a theory it's due to mineral build up in the boiler that causes some weird tasting water. Even if it's descalled *maybe*.

*Update*
My silvano steam wand still emits a strange metallic smell at first, I just let out the steam for a 30sec, to a minute before using it, hopefully inhalling some of the metallic smelling steam doesn't affect my health negatively. But at least it goes away and doesn't go into my milk.
The water still tastes pretty decent through the machine *unlike my old one*. I've been using it everyday for a few months now. I'm worried if I don't use it for a while and then go back to using it, then it will develop a strange taste from water being left in the bioler for a period of time, I think that's how my old one ended up tasting so funny.