Tasted Your Reservoir Water Lately?

[Dogshot]

I used to top up my reservoir every night, and change the water every other night. Then one (change) night when dumping the remaining water, I thought I would try it to see if the reservoir was imparting any taste to the water. Well, it wasn't as bad as one of those cheap sports bottles, but there was a slight plastic-container taste to it - enough to induce my head into a nutating motion anyway .

Now I dump the water every night, and the taste is barely discernable. Why does a disposable water bottle keep water for 2 years without imparting a taste when re-usable plastic bottles impart taste in hours? And what is the reservoir in the GS3 made out of - maybe LM has solved the reservoir issue.

For those who have plumbed in units - yes, this is yet another reason why you have a plumbed unit...yada yada (sour grapes, it's not really that big a deal, etc.)

Mark

[HB]

And what is the reservoir in the GS3 made out of - maybe LM has solved the reservoir issue.

The outer back shell forms half of the GS3's water reservoir. It's made of stainless steel.

[Teme]

My concern with the GS3 reservoir is cleaning. You cannot take it out, i.e. you have to clean it in situ. Not quite perfect imo.

Br,
Teme

[HB]

Bingo. As I understand it, that was one reason its NSF approval is pending.

[1st-line]

I used to top up my reservoir every night, and change the water every other night. Then one (change) night when dumping the remaining water, I thought I would try it to see if the reservoir was imparting any taste to the water. Well, it wasn't as bad as one of those cheap sports bottles, but there was a slight plastic-container taste to it - enough to induce my head into a nutating motion anyway .

Now I dump the water every night, and the taste is barely discernable. Why does a disposable water bottle keep water for 2 years without imparting a taste when re-usable plastic bottles impart taste in hours? And what is the reservoir in the GS3 made out of - maybe LM has solved the reservoir issue.

For those who have plumbed in units - yes, this is yet another reason why you have a plumbed unit...yada yada (sour grapes, it's not really that big a deal, etc.)

Mark

Slightly off topic.... how does the water taste on dual boiler machines that have large dedicated boilers for espresso extraction?

[HB]

That question has come up a few times in different forms (e.g., Can water go stale? and What E61 & Grinder would you buy for <$2K?), but I don't recall any blind taste comparisons of brew boiler versus fresh water. I'll pose my suggestion again for any owner of a moderate to large dedicated brew boiler espresso machine (e.g., Expobar Brewtus, Isomac Amica, Fiorenzato Colombina, or multi-group commercial machine):

Of course, there's an easy test: Assuming the machine is squeaky clean, draw eight ounces of water through the group and let it cool. Compare the sample blind against fresh water, also at room temperature. What is the difference in taste, if any?

I did have the Brewtus for a few months and never noticed an issue, but I didn't specifically compare the water drawn from a squeaky clean machine after it sat idle for n hours / 1 day / n days. The boiler material would probably make a difference, e.g., I would be surprised if a stainless steel tank imparted a taste after prolonged downtime, but a copper one might.

(Of course the simple answer is don't worry, drink more espresso.)

[Dogshot]

Of course, there's an easy test: Assuming the machine is squeaky clean, draw eight ounces of water through the group and let it cool. Compare the sample blind against fresh water, also at room temperature. What is the difference in taste, if any?

I would try this test, but it does not control for the possibility that the HX and/or group is imparting taste. If I had access to a traditional HX machine as well, I think the blind test between the 3 samples would be a reasonable way to find an answer to the question. Ultimately I have to agree with Dan's final comment and go with the simple solution.

Mark

[HB]

I would try this test, but it does not control for the possibility that the HX and/or group is imparting taste.

Yes, I thought the same thing this morning.

A better test to determine if a double boiler imparts a taste would be to flush down the boiler completely, refill it, wait until the boiler stabilizes at brew temperature, and then draw a sample. Then leave the machine idle for 24 hours and draw another sample. Taste the two samples at the same temperature (room temperature or heated to say 150F).

[T.J.]

To be honest, I don't really think there is a quick solution other than changing the reservoir water prior to using the machine each day. For this reason, I am inclined to feel that removeability of the reservoir trumps the material it is made of.
I won't hold my breath for any manufacturer to solve the pitfalls of "still" water.

It is quite important for the reservoir to have a built in water softener that can be changed regularly based on consumption. If a machine with a reservoir does not have a softener, I'd expect poor long term quality results.

That is my 2 cents....not quite on topic.

Low consumption (less than 30-50 shots per day (two group units 1 liter boiler)) dual boiler systems do have a history in Europe of fielding low quality shots. Unfortunately, with a developing specialty coffee culture in its infancy here in the USA, most of the attention has been to temp. stability and not enough attention has been paid to pure shot extraction quality. The poor shot "taste" quality has been attributed to water sitting in the coffee boiler doing nothing and growing "still". In fact, all recent La Cimbali dual boiler super-automatics have a feature that empties the coffee boiler each night and refills it with fresh water from the main. This was done to improve taste and increase the life of the boiler through scale reduction. There is no shortcut around stale water in a coffee boiler on a dual boiler machine......one of two things must be done otherwise coffee quality will suffer.

1 Drain the coffee boiler regularly.
2 Produce enough coffee to naturally replace the coffee boiler water through regular usage.

Our (La Cimbali) R&D in Milan spent hours upon hours trying to find a solution to the stale taste of water coming out of our dual boiler systems. We manufacture over 5,000 super-automatics per annum...most of these have dual boiler systems. In fact, we manufacture the most commercial dual boiler espresso machines in the world through the production of our super-automatics....we therefore have a lot of information on these systems along with their pros and cons. Our conclusions, after dozens of tests, bore the result that the coffee boiler, if left unused or working with low volumes, was prone to poor taste extraction. A benefit of HX systems for low volume users.

In super-automatics, we like the dual boiler primarily because it allows for the automation of independent systems (steam system vs coffee system) without sacrificing taste. Our single boiler super-automatic systems use our newest HX technology and achieve a great result in the cup....however, we are able to automate fewer functions because of this.

Our conclusions have shown that the HX systems seem to work as well as dual boiler systems in producing quality shots. We have not seen any data which holds one technology over the other. We employ dual boiler systems in super-automatics to increase automation and programmability of all functions and parameters. We do not employ dual boiler technology because it fields a better shot in the cup.

[randomperson]

T.J. -- I found your post fascinating -- it actually tipped me over the edge in my decision to buy La Valentina over the Brewtus II, as I had long been concerned about water sitting essentially forever in a home dual boiler environment. At low usage, it just doesn't seem like the right thing to do.

I know definitive taste tests haven't been done in this context, but it is certainly true (to my taste buds, anyway) that drip coffee is markedly improved by using fresh water rather than water that has been left in the drip coffee machine tank overnight. Similarly, tea tastes quite different if the water is not freshly boiled but is rather reheated (I'd never use an espresso machine's water for tea!). It is only logical that water from a dual boiler espresso machine would degrade comparably.

That said, I imagine not everyone would notice the difference -- or if they do, they might not care, as it may be primarily in the comparison between the two that the difference becomes obvious.

Still, it does give one pause if one is buying for home use for low volume consumption.

[DavidMLewis]

Slightly off topic.... how does the water taste on dual boiler machines that have large dedicated boilers for espresso extraction?

I've tested this on my Reneka Techno, which has 1.4 liter boilers for both brew and steam, with the steam boiler being fed from the brew boiler. I've done it in the usual fashion, by running water into a cup, letting it cool, and tasting it. The results are interesting: both boilers are of identical construction, with a copper tube captured by brass end plates, but the water from the brew boiler, which is completely full, never picks up a taste, while the water from the steam boiler, which is partially full, goes stale enough that I wouldn't use it for anything except heating cups. The steam also picks up a taste if I don't do any steaming for a day or so.

Best,
David

[CoffeeOwl]

There are two issues regarding the water in dual boiler machines: water for espresso brewing should be fresh, while the water in the steam/hot water boiler doesn't need to be fresh, even for an americano - I believe.

[Fullsack]

The reservoir in my old Brewtus II began to look and smell like a neglected fish tank after about a month. I believe its proximity to the hot boiler had a lot to do with that.