Hello everyone,
I'm new to this forum, even I used it for some time as research tool Very useful thanks ! So here is my first question:

I'm researching the best Water for my Rocket, but since I'm live in Dubai it seems quite a unusual quest. The goal, besides good espresso, is to minimal scale and service need for my HX Machine since I'm far away from any service point in case of problems.

General Dubai Water comments
- Almost all the water here is desalinated seawater, including 99% of the local produced drinking waters - hence super low hardness in general.
- Connecting the Machine to the tap is without RO is out of question - the water is to soft, has high chlorine and I have limited trust into the in-house storage tanks etc. In summer, even the cold tap water can be as "cool" as 30C/86F !
- There is only one local real Mineral Water: Producer: Good taste for drinking but TDS/Hardness Values tend to fluctuate big according to the batch of Water. All the other waters are filtered / mineralized tap water
- The few imported bottled waters as super expensive! Volvic for example would be over $2 for 1,5L.

I found now the following Water which seems a good compromise. I know the Alkaline Level is low, but its among the higher ones in the region.
The only concern left is that the La Marzocco Water Calculator says slightly corrosive.
(http://techcenter.lamarzocco.com/jsp/Te ... ulator.jsp)

Here are the details:
TDS 110
Total Hardness 73
Alkalinity (calculated from Bicarbonate)) 24.6
PH 7.3
Calcium 8
Magnesium 13
Sodium 8
Potassium 2
Chloride 40
Sulfate 5
Bicarbonate 40

La Marzocco says the LSI Index is slightly corrosive but no scale build up

Any comments?

cheers Marco

Hi Marco -

Except for the chloride numbers, that water would be good. Chloride is a corrosion concern, and for that reason La Marzocco recommends that it be below 30 mg/L, Synesso recommends that it be below 15 mg/L. If your alkalinity is good you can be a little less concerned.

The LSI on that water comes out negative even at high boiler temps. At 8 mg/L calcium ion and 13 mg/L magnesium ion, you have a calcium hardness of only 20 mg/L as CaCO3, so it certainly won't deposit limescale.

Also, I noticed that your alkalinity/bicarbonate numbers don't seem in close agreement. 40 mg/L bicarbonate ion equates to 33 mg/L bicarbonate alkalinity as CaCO3 (not 24.6).

With that borderline high chloride I think I'd keep looking. If I did use it I might boost the alkalinity a bit just to alleviate that worry. (For example, If you made a concentrated solution of 8 g potassium bicarb in a liter of water, then add 5 ml of that concentrate to each liter of brewing water you would get a 20 mg/L as CaCO3 increase in alkalinity. )


Edit addition: For anyone looking here for data on Dubai water, be aware that swisscraft's water discussed above is a bottled water and is not Dubai tap water. Numbers for Dubai tap water are hard to find. It is primarily from desalinization plants, I think with minerals from wells mixed in, and probably up in the 70 - 80 mg/L range for chloride ion based on this 2016 report: https://www.waterclub.ae/images/DEWA.pdf

Thanks a lot Pat for your Feedback, I have two follow up questions


What got me confused is the way you calculated the alkalinity from the bicarbonate level. I used Jim Schulmans Water FQA wich says multiply bicarb by 0.82 - hence my calculation - how did you calculate?

Then, thanks for adding the formula for boosting adding alkalinity, will certainly use that as chloride is a concern, and its unfortunately very common here. And here is the last question: Is there an advantage to use potassium bicarb over sodium bicarb and how would that affect the total hardness in regards of limescale?

Thanks !

swisscraft wrote:how did you calculate?

You used the correct factor; I think your calculator failed you. 40 x 0.82 = 32.8

swisscraft wrote:Is there an advantage to use potassium bicarb over sodium bicarb and how would that affect the total hardness in regards of limescale?

Sodium bicarb would work - you'd need slightly less - around 7 grams instead of 8 to get the same bicarbonate. The preference for potassium bicarb is that it would not increase your sodium. Your water is already close to the SCA ideal for sodium. Professor Pavlis, rpavlis on this site, makes the sensible argument that since coffee beans are already very high in potassium you can safely add more without expecting any effect on taste.

Adding potassium or sodium bicarbonate increases the alkalinity but not the hardness. As you know from Jim's water FAQ, this would push it towards depositing scale. But this water is a special case because it is unusually high in magnesium and low in calcium. (Jim's tables are conservative and assume that most or all of your hardness is calcium hardness.) If you bump the alkalinity all the way to 60 mg/L, and calculate a Langelier Saturation Index* on :
TDS 110 mg/L
calcium hardness 20 mg/L as CaCO3
alkalinity 60 mg/L as CaCO3
pH 7.3
temperature 120C (appx 1 bar)

You come out very close to neutral

* An online calculator is available here. Or you can use the equations in Jim's FAQ. The two produce slightly different results, but the difference is not significant.

WOW Pat thanks very much for the detailed information! I really impressed with you and this forum!

I noticed that the water I posted had 30 Bicarbonate and not 40 - so stupid typo instead of wrong calculation, really sorry of that - all other values are as posted.

I will follow your advice and use potassium over sodium. Following your calculation, and checking the calculator I would assume an increase of 40mg (with 16g /1L concentrate then 5ml per liter ) brings me into the desired values.

Once again - Thanks very much !!

Reading this thread made me think about how important it is to periodically test one's water if one is using additives in order to prevent damage to the machines and improve the taste in the cup.

I say this because the numbers that are published by my local water supply company differ from what is coming out of my tap. On top of that the composition of the water coming out of my tap varies, depending on the time of the year.

Marco: Did you have your water tested by a laboratory, or are you using the numbers published by your water supplier?

Hi Cruiten,

I first compared the labels on the Water Bottles (as said, I'm not using Tap Water for several reasons, one is, we do not even get information from the Water Company). Then I tested the Water myself with a TDS Meter, GH/KH Test and some PH Strips to verify. Here is the list with the tested Waters: Some information are missing - with the tips from Pat I currently choose No. 8

Pat, all, just want to share my new findings:

After your concerns about Chloride and reading further into it I will change now to Water No. 3. I will push the Alkalinity with either Sodium or Potassium bicarb (Sodium in this water is very low).
If I'm correct adding 14g Sodium bicarb to 1 Liter and then add 5ml to each liter of "machine' water to boost the alkalinity by 40mg which brings me to the 50 range - I should be again close to neutral.

Special Thanks to you Pat for the detailed help !

cheers Marco

Your recipe for bumping #3 to 50 mg/L alkalinity looks right. That gets your chloride better. That water does have the downside of more sulfate, but I think it's still probably a better choice than #8. It's awfully easy to get caught up in analysis paralysis on this water issue.

If you want more reading on chloride and sulfate, you can refer to a couple of rpavlis posts here and here.

And speaking of professor Pavlis, I think you might want to consider going with his approach - simply using distilled or purified with enough bicarbonate added to get you around 50 mg/L (as CaCO3) alkalinity. Lots of folks on this site prefer it, and refer to it as the rpavlis recipe. The big advantage is that you have zero need to descale and no worries about corrosion from chloride, sulfate, or acidic water. In your recipe strategy you would put 17.5 grams of sodium bicarb (or 20 grams of potassium bicarb) in the 1 liter concentrate bottle and use the usual 5ml per liter of brew water.

Nice chart, by the way! FWIW, I did notice a wrinkle in your row of calcium numbers. The SCA numbers (range 17-85, ideal 68) are for calcium hardness mg/L as CaCO3, and the rest of the numbers in that row are for calcium ion mg/l. The SCA numbers expressed as calcium ion mg/L would be range 7-34, ideal 27. ( 1 mg/L calcium ion is equivalent to 2.5 mg/L calcium hardness as CaCO3.)

Hi Pat,
seems we never stop learning - Thanks!

The water situation in the middle of the desert seems to be rather typical - its sparse at best
I cannot find any distilled water in reasonable sizes (at least in common shops & online), the produce it but in bigger quantities for the chem industry only. Deionised water is available, and while I'm sure it will be according to specs from a mineral content I would not dare to use it as would have no idea how the standards are here in terms of organic molecules, viruses or bacteria as it comes from a small factory in the middle of a heavy industry area.

Given that difficulty and your elaborated advice, I ordered now a small home RO system & will use Potassium bicarb - I think in the long term it will be the best solution with the least headache.

Thanks very much
Marco