Will BWT pitcher fix my water? Or make rpavlis

Water analysis, treatment, and mineral recipes for optimum taste and equipment health.
111a111sk

#1: Post by 111a111sk »

Hi,

I see in my kettle slight but visible limescale already after half a year of usage. The taste of tap water is fantastic though. Now I'm getting a rather high-end espresso machine which I'd like to survive well over 10 years, so I think the water must be treated.
Here are water quality metrics in my city: (first/second spring) https://www.wien.gv.at/english/environm ... esult.html

Will a BWT pitcher with the magnesium remineralising cartridge make the limescale depositing a non-issue while not messing up the taste qualities?
https://www.bwt.com/en-gb/products/filt ... ter-3-pack

Does the added 30ppm magnesium create some deposits?

Is this magnesium + zinc any useful? https://www.bwt.com/en-gb/products/filt ... water-zinc

// edit1, I did a lot more reading, it's been rather confusing
- Many mentions of fully replenishing the water in boilers being highly effective prevention.
- There are a few mentions of scaling with TWW (even espresso mix).
- TWW availability in Europe is problematic, it results at €0.15/l + the distilled water where I live is €0.30/l ... the scale risk is present, and dumping a boiler volume, idk, weekly is not negligible.
- The most helpful thread: Seeking input on BWT-jug-filtered water
- The BWT Mg seems to be pretty effective but depends on the tap water. Would require measurement and possibly diluting with distilled. Even if I replace cartridges every 50l, it'd be €0.09/l which I'm fine dumping weekly.

// edit2, few hours of reading later
Discovered some scale-avoiding DIY recipes like the rpavlis and I'm inclined towards that. It costs around nothing + the distilled water. No dumping needed. But not many mentions or comparisons of its effect on taste.
TWW espresso is also potassium bicarbonate + magnesium sulfate + calcium citrate.
Few questions here:
- Is potassium bicarbonate alone enough not to mess with the taste? At 0.1g per liter
- Does magnesium sulfate cause scale depositing?

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homeburrero
Team HB

#2: Post by homeburrero »

Given your two edit additions I think you've found some or all of the answers to your questions.

Your Vienna water will benefit by softening, and looks like a reasonable candidate for that BWT filter because it has plenty of carbonate hardness and not much chloride. (These filters use a WAC resin which will acidify your water a little.)

I think you could get a little better softening assurance with their other filter: https://www.bwt.com/en-gb/products/filt ... -water-3er . That one does not add magnesium, but I think that's largely a snake oil feature. If you use that one and still want to be cautious you could use a drop titration test kit for GH (total hardness) and KH (alkalinity) on the filtered water, and do your own limescale risk estimations with the help of Jim Schulman's Insanely Long Water FAQ.


111a111sk wrote:Does the added 30ppm magnesium create some deposits?
Their 'patented Mg technology' uses a resin where most of the calcium ions in the water are replaced by hydrogen ions, and some of the calcium ions are replaced by magnesium ions, so the increased magnesium is offset by decreased calcium, netting you a lower limescale risk.



111a111sk wrote:Discovered some scale-avoiding DIY recipes like the rpavlis and I'm inclined towards that. It costs around nothing + the distilled water. No dumping needed. But not many mentions or comparisons of its effect on taste.
TWW espresso is also potassium bicarbonate + magnesium sulfate + calcium citrate.
Few questions here:
- Is potassium bicarbonate alone enough not to mess with the taste? At 0.1g per liter
- Does magnesium sulfate cause scale depositing?
It's true that there are no blind and controlled taste tests of rpavlis vs. water with some hardness minerals. You can always do your own, trying water with and without hardness minerals. The rpavlis recipe is simple, tolerates being concentrated in the steam boiler even if you neglect to manage that with purging or flushing, has no objectionable ions (chloride, sulfate), so is a good choice if you find no taste benefit from hardness minerals.

Magnesium and sulfate alone would be very soluble. But you have to be aware that all the ions are in there ready to get together with with other ions. Magnesium and bicarbonate ions can produce MgOH and MgCO3 scale at high pH and high concentrations. Sulfate and calcium ions can produce calcium sulfate deposits, which are difficult to descale.
Pat
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111a111sk (original poster)

#3: Post by 111a111sk (original poster) »

Oh I see, so the rpavlis formula prevents scale only because there is no Mg nor Ca. Not that it's a property of KHCO3. If I add MgSO4, heated it'll start forming MgCO3 scale, right?

Well, I think I'll do best just giving both (probably the most softening BWT) a try. I'll get the drop test kit and compare the outcome myself. The taste difference too. I'll sure post an update in a few weeks. Thank you

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G.F.

#4: Post by G.F. »

Dr.Pavlis recipe plus potassium bicarbonate, works excellent for me, no worries of limescale, filters, RO, GH testing, etc.

111a111sk (original poster)

#5: Post by 111a111sk (original poster) »

Dr.Pavlis recipe plus potassium bicarbonate
Isn't Dr. Pavlis' recipe just potassium bicarbonate?

By the way, did you maybe experiment with magnesium sulfate?

Found this test/measurement of flavour compounds extraction: http://www.youtube.com/watch?v=d4C1DXpscSo
It quite clearly (log y-axis) shows a raise until 60-80ppm hardness. I guess stock rpavlis is near 0? Or does potassium bicarbonate contribute to hardness?

User avatar
G.F.

#6: Post by G.F. »

111a111sk wrote:Isn't Dr. Pavlis' recipe just potassium bicarbonate?
Distilled / Potassium Bicarbonate Water with Fill Sensor
111a111sk wrote:By the way, did you maybe experiment with magnesium sulfate?
I'm afraid not.
111a111sk wrote:It quite clearly (log y-axis) shows a raise until 60-80ppm hardness. I guess stock rpavlis is near 0? Or does potassium bicarbonate contribute to hardness?
Contribute to raise PH.

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homeburrero
Team HB

#7: Post by homeburrero »

111a111sk wrote:Found this test/measurement of flavour compounds extraction: http://www.youtube.com/watch?v=d4C1DXpscSo
It quite clearly (log y-axis) shows a raise until 60-80ppm hardness. I guess stock rpavlis is near 0? Or does potassium bicarbonate contribute to hardness?
Rpavlis water is zero hardness. The bicarbonate is needed to buffer acids - keep the pH from going acidic. Buffering capability is also referred to as alkalinity, the standard 100 mg/ml potassium bicarb has an alkalinity of 50 mg/L CaCO3 equivalent (or 5.0 French degrees, 2.8 German degrees, 1.0 mEq/L ). Standard SCA recommendation is 40 mg/L or more for espresso machine water.

That was an interesting study. You can see it written up a little more clearly here: https://www.sevenmiles.com.au/editorial ... or-coffee/ and see some discussion on HB here: The Science of Perfect Water for Coffee - Seven Miles Coffee, UNSW . I was hoping that it would be written up for publication so we could see more details about the water, the coffee, methodology, some data and statistics, etc, but unfortunately I don't think that ever happened.

One of the better examples of a well designed blind taste test is discussed on page 20 of this Cafe Europa magazine: http://scae.com/images/caffee-europa/CE61.pdf
They carefully taste tested (cuppings, not espresso) two coffees using three waters, with approximate GH:KH (as CaCO3) values of 95:58 (high), 78:42 (medium), and 51:22 (low). Where they did see statistically significant differences it was the low mineral water that scored highest.

Dr Pavlis' would sometimes point out that the liquid flowing through a coffee bed was loaded with hardness minerals, especially magnesium, dissolved from the coffee itself. So a relatively small amount of hardness that comes in with the brew water would not be expected to make a difference in extractions.

Conventional wisdom for a while was that you needed divalent cations (hardness) in the brew water to get high extractions. Simple refractometer measurements have not demonstrated that to be true.
Pat
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