Ive been using Third Wave Water for a bit and am curious, if using this water is it necessary to descale the machine every so often and also having a filter in the reservoir?

That water is low in calcium and low in bicarbonate, so you don't expect limescale and don't need to descale.

In theory, the high sulfate might get together with the small amount of calcium to produce calcium sulfate deposits, which normal descaling would not remove anyway. As far as I know this has not been reported by users of TWW, but it still would be prudent to avoid letting the water in the steam boiler become highly concentrated, which would increase the risk of that.

With TWW supplemented purified water you don't need or want a filter in the reservoir. A carbon filter would not hurt but any of the softening filters would work against you -- removing the calcium and magnesium ions that you went to the effort and expense of adding with the TWW supplement.

What are the signs of calcium sulfate deposits? Without rehashing old territory, my trials and tribulations with Third Wave were fairly obvious and documented by my vendor.

It will be hard to distinguish by appearance from limescale. Drywall and gypsum are calcium sulfate. If you scrape some off and put in a cup of vinegar it will not dissolve and bubble off CO2 like limescale would.

I seriously doubt that calcium sulfate is a culprit behind the mystery of: Boiler PID Sensor Problems with 3rd Wave Water . Unless you are drastically concentrating the water in the steam boiler you would not expect it to be precipitating.

I completely agree that the issues facing Lelit are different than what I encountered. But when my vendor removed a part of the machine to examine and diagnose the issue, the part was covered in limescale (far worse than you'd think after I only used 8 packets or so).

The reason I mention this is that your comment struck a chord with me -

homeburrero wrote:That water is low in calcium and low in bicarbonate, so you don't expect limescale and don't need to descale.

As far as I know this has not been reported by users of TWW

Not sure that I agree...

Auctor wrote:[The reason I mention this is that your comment struck a chord with me -

homeburrero wrote:
"That water is low in calcium and low in bicarbonate, so you don't expect limescale and don't need to descale. As far as I know this has not been reported by users of TWW"

Not sure that I agree...

Yes, I forgot about your experience, which you reported a while back and I clearly saw. So I shouldnt have said that scale w/ TWW has not been reported.

I hope any others with a similar experience will weigh in. And let us know if you have more info about your scale issue, especially whether it might be related to a lot of steaming without regular flushing or draining of the steam boiler.

Just crunching the numbers on what is reportedly in the TWW espresso formula we expect the properly dosed water to have about 42 mg/L calcium hardness (as CaCO3) and about 20 mg/L carbonate/bicarbonate alkalinity (as CaCO3). (Compare that to the longstanding SCAA standard of 68 mg/L calcium hardness and 40 mg/L alkalinity.) Those numbers, especially with the low bicarbonate, would indicate that limescale (CaCO3) precipitation even in a hot steam boiler should be unlikely.

P.S.
I moved this topic from Espresso Machines over to the Water forum

So what I gather from everyone is that TWW contains calcium and it's actually bad for the boilers but does make espresso taste good. Now would using a Barista Hustle recipe let you avoid descaling all together? I kind of don't like the idea of putting chemicals in my machine so I'd like to descale as minimal as possible. If it must be done, how often should it be done with Barista Hustle or TWW being the main source of water?

sfaticat wrote:So what I gather from everyone is that TWW contains calcium and it's actually bad for the boilers but does make espresso taste good.

That would be a misunderstanding. High calcium levels may cause problems with limescale (CaCO3) accumulations if you don't monitor and descale when necessary. Any natural water will contain some calcium, as will any RO water that is remineralized with a calcite cartridge, so it's been in the water of espresso equipment for ages. And often you see references to "protective limescale" which is the idea that you want enough calcium and carbonates in your water to produce a healthy layer of limescale to help protect from corrosion.

The counter-argument to protective limescale is that it is not deposited uniformly on the surfaces and that it's porous and not that protective. Also if your water is depositing limescale it will accumulate, and eventually will require you to descale, which means harsh acids. And if you wait too long before descaling you can get clogs from loosened limescale moving into narrow passages. So many vendors are now advising that users never descale their machines, which means keeping the calcium and alkalinity at low enough levels that you do not accumulate limescale. The bible for doing these scale or no-scale estimates for natural water in espresso equipment has been in use for decades: Jim Schulman's Insanely Long Water FAQ.

There is some conventional wisdom that divalent cations (hardness minerals like calcium and magnesium) are needed for tasty extractions. The old SCAA recommendation suggested that a calcium hardness of 51 mg/L - 68 mg/L (as CaCO3) was needed for a "Superior brew". (See Good references on water treatment for coffee/espresso )

More recently a lot of folks have argued that you can use magnesium rather than calcium, or that you don't need any hardness minerals at all to get tasty espresso extractions.

sfaticat wrote:Now would using a Barista Hustle recipe let you avoid descaling all together? I kind of don't like the idea of putting chemicals in my machine so I'd like to descale as minimal as possible. If it must be done, how often should it be done with Barista Hustle or TWW being the main source of water?

My opinion is that you should not expect any scale issues with most of the Barista Hustle recipes nor with the TWW , provided you are taking care not to over-concentrate the water in the steam boiler due to taking steam out without ever purging or draining the boiler. If you want to play it extra safe, then by all means use the rpavlis water recipe - 100 mg of potassium bicarbonate per liter of purified water. That one not only has no scale minerals, it also is free of any sulfate, chloride, or citrate that might be undesirable.