Water from brewhead of my Duetto doesn't taste that good. It's not the softener/carbon filters, since output from that tastes great.

I backflush w/ detergent ~every week, and scrub after each shot usually. I took off the screen, cleaned... and running straight from dispersion screw also tastes bad.

So I descaled it 2 nights ago (both boilers) using Urnex Dezcal... 1st time in 2 years of use -- I used 1 packet per 500ml, the commercial strength. After flushing for hours, I see metal particles in water.

Yesterday, I followed Eric's tip Checking an E61 Espresso Machine for Scale on cleaning the mushroom... (man, it had some nasty scaling and flaking... but got it very clean... and also the chamber).

I was sure that will fix it.... but still after many more complete boiler flushes, I still see some metal flakes, and it tastes metallic.

Espresso is ok, I think even improved a bit after all this. But I wonder if I can get it better. Where are the rest of the flakes coming from? Would another descale help?

....should water out of machine taste as fresh as straight out of the filters? (in my taste tests, i also drain the boiler, and then fill a cup.... so it's fresh, not water that stayed in boiler for a while)

Thanks for any advice!

With the recent thorough cleaning of the group I would expect it will take a few pulls to get a coating (coffee oils, metal oxidation, etc.) on the metal parts. I think that the taste will improve.. Just keep an eye tongue on it.

How does the espresso taste?

It tastes pretty good... I think there was a slight improvement even after the mushroom scrubbing...

It's surprising, since the water quality out of machine is so inferior to the tap or filtered water.

That's sweet maria's coffee I guess.... soooo good it overpowers poor water


I'll keep flushing a lot and see if it'll improve in a few weeks.... I was wondering though how realistic it is to get it tasting the same as fresh water not passed through the machine.

Metal particles are, with 99-44/100% assurity, originating from the mushroom. I would just soak the mushroom in some white vinegar for an hour or so and be rid of all that "fake" chrome plating. Use a 1 cup pyrex glass and fill to the threads with vinegar.

Descaling is "overblown." What is so important is to be aware of the water quality coming into the machine and make appropriate adjusments to the source. There exists a plethora of threads on this site of "problems" appearing after descaling - whether it was done right, wrong, or somewhere in between.

I would say that you are doing the detergent backflushing too often - but this is really a grey area. It is far better to remove the screen and gasket (get a spare set), "scrub" the dispersion area while the screen soaks, and replace with clean parts.

Metallic flakes and a metallic taste to the water is relatively common after a descale. There is a lot of incidental chrome plating inside the group. After a descale a lot of that chrome overrun plating will flake. After a lot of flushing it will wash out of the system until your next descale. Eventually all that extra chrome inside the group will wear off and subside. For more information look at

Metallic particles/flakes in the water...

Sorry, I read that thread and kinda missed the details in the last page where he takes out the lever to solve it. I should of replied there.

I took it out again, and the mushroom/chamber had a bit of crud on it again (don't have pre-clean mushroom pic):


I tried soaking mushroom again for an hour, it didn't seem to strip off any more than before (u suggest to sand the rest it off?):


I cleaned the chamber again:


...I think there's a slight improvement, but still a bit of off taste. Maybe worth to take the lever out tomorrow and take a look... otherwise, looks like I'll just need to wait it out.

erics wrote:Descaling is "overblown." What is so important is to be aware of the water quality coming into the machine and make appropriate adjusments to the source

I use the softener/carbon filters chris recommended... I change softener every 6mo and carbon every 12mo. Are you recommending not to descale? or adjust filters I use? Even though I maintained them I had a buildup there... it makes me wonder what the boilers look like, since it took a scrubbing to get that gunk off of the mushroom.

Thanks for the tips Dan.
I guess I'll see how it recovers from this descaling taste wise, and probably do it in 2 years again... it seems like I shouldn't skip it completely with my water hardness.

HB wrote:I was talking with our local retired chemist, Bob Barraza, about using distilled water in steam boilers and the taste of heated water. He pointed out that when water is heated, it has great affinity for whatever possible solute is available in the environment

This sort of thought is what made me wonder the question in the title of the post... how fresh should it really taste... if most people that make "exceptional espresso" taste some degradation out of brewhead water, I won't be as curious to try to get it super clean tasting either.

I did a test while machine was cold. After flushing out boiler, water tasted good... just like the tap. After machine was heated it, cooled water sample tasted bad again. I'll see if some scale coating in time will change this...

Here's the mushroom after a day of use... I wonder what all that green stuff is (no detergent was used).