Scale after 18 months using Volvic

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
Wattbe

#1: Post by Wattbe »

Thought it might be worth sharing my experience of using Volvic in my espresso machine for the benefit of others.

As I couldn't plumb in my machine due to its location in the house, and after much research, I decided to use Volvic based on the general consensus that it would be a safe bet and would hopefully avoid the need to descale.

However, 18 months later, I noticed that my machine became gradually more noisy when it was on but not being used.
When it was brand new, I'd only hear an occasional 'fizz' as the heating elements cycled on to maintain the set temp. But 18 months on and it was making a constant fizzing noise that was gradually getting louder.
I decided to take a look inside the steam boiler and saw evidence of scale. As a result, I removed the element and found that there was indeed more scale than I expected.
Volvic does have a higher silica content than what I've read is ideal, so not sure if it's silica scale?
After replacing the element, the machine is back to normal and to prevent it from reoccurring, I've switched to remineralised RO water.
For completeness, the boiler was set to 127 degrees C which provided a steam pressure of 1.7 bar.
The brew boiler, which is set to 95C, is fine but at the higher temps in steam boilers, Volvic seems to scale enough to require descaling every year.
Here's a few photos.




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homeburrero
Team HB

#2: Post by homeburrero »

Thanks for the report - always good to see some real world experience.

The conventional wisdom from users and forum reports is that Volvic will require infrequent to no descaling. One trustworthy and technical expert on the UK forums reported no scale after 3 years use. And others report traces of scale and doing a descale every other year or so. (conversation link: https://coffeeforums.co.uk/topic/28103- ... ent-393467)

Of course it depends, especially on your boiler temp. If you do an LSI for your 127 ℃ on the Volvic numbers (alkalinity 63, Ca hardness 33, TDS 110) you get an LSI pHs of 6.89, which indicates no scale at the bottled pH of of 6.5. But you do expect slight scale if you use the effective boiler Puckorius* pHeq at that 63 mg/L alkalinity, pHeq = 7.07. So you might well expect light limescale (CaCO3) at your steam boiler temp. If you have a tendency to routinely use the steam wand without occasionally drawing from the boiler water tap then you would be concentrating the minerals in the steam boiler, causing more scale.
Wattbe wrote:Volvic does have a higher silica content than what I've read is ideal, so not sure if it's silica scale?
Good point. Even though the online analysis of Volvic doesn't show the silica numbers, earlier reports indicate that it has in the neighborhood of 30 mg/L silica as SiO2. Not sure if that's enough for concern - silica scaling seems to be very complicated. I don't think that silica is what you see in your picture. The Handbook of Water and Wastewater Treatment says "Silica scales are typically very hard, glassy, adherent and difficult to remove."

Probably too late now, but an easy test to help know a lot about a scale residue is to scrape some off into a cup and add some vinegar. If it fizzes or dissolves it would be a typical carbonate. If it doesn't it's something else - most likely a calcium sulfate scale.

* pHeq = 1.465 x log10[Alkalinity] + 4.54
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

Wattbe (original poster)

#3: Post by Wattbe (original poster) »

Thanks for the reply Pat - that's an interesting read.
I've always deliberately drawn water on a daily basis from the steam boiler to ensure it remains fresh and to reduce scale and I was surprised/disappointed that the machine had scaled that much after 18 months.

Thanks to your advice in previous threads, I seem to have my RO water at a point now that it tastes good but will hopefully avoid further scale.

I'll keep you posted!