Which RO water setup for a plumbed in espresso machine?

[esbndk]

I recently found out my water is too high in chloride, so I am looking for an RO system.

There must be other people looking for the same info, in similar circumstances, so I created this topic.

I would like to keep my machine plumbed in. But then I need to look at remineralisation/calcite filters.

Having no understanding about water chemistry I find myself drowning in questions;

They all contain different minerals and quantities?

How much of those minerals will end up in the water? Can I trust the label?

So I found this remin filter which is available easily in my country (Denmark): GlobalWater GW-MIN-L2

https://sklep.osmoza.pl/mineralizing-ca ... p-734.html

Cations: Ca2+: 34mg/l Mg2+: 12mg/l Na+: 22mg/l K+: 8.5mg/l
Anions: CO32-: 10mg/l SO42-: 0.3mg/l Cl-: 0.8mg/l F-: 0.06mg/l

So sulphates and flourine and chlorides? Are they just being honest about unavoidable contents? Or should I find another?

Anyone who has done this? Which membranes did you use, how high capacity is needed in GPD?

My machine is a Lelit Bianca Can I just measure the water debit and maybe double it?

[CarefreeBuzzBuzz]

Before you decide on RO, especially with remineralization, have you read this thread:
Espresso Cart - Goodbye Plumbed In

Only reason I ask is the results of an RO system will vary over time. If you want to never worry about what's going on, the cart is your alternative. Once set up the time and maintenance aren't a bother IMO. And it's worry free about what the cartridges are doing or not.

[homeburrero]

So I found this remin filter which is available easily in my country (Denmark): GlobalWater GW-MIN-L2

https://sklep.osmoza.pl/mineralizing-ca ... p-734.html

Cations: Ca2+: 34mg/l Mg2+: 12mg/l Na+: 22mg/l K+: 8.5mg/l
Anions: CO32-: 10mg/l SO42-: 0.3mg/l Cl-: 0.8mg/l F-: 0.06mg/l

So sulphates and flourine and chlorides? Are they just being honest about unavoidable contents? Or should I find another?

Anyone who has done this? Which membranes did you use, how high capacity is needed in GPD?

My machine is a Lelit Bianca Can I just measure the water debit and maybe double it?

That one is interesting in that they attempt to quantify what minerals. They don't clearly specify how they arrived at those concentrations, and the numbers look fishy for dolomite (which they claim is their mineral bed). It may be calcined dolomite, which is primarily MgO and CaO, which might explain the oddly low CO3-- number.* The relatively small amounts of other trace minerals don't look like a problem. From the specs I see, I have no idea how this filter might perform in terms of the alkalinity and hardness that you'd get in a real world RO system feeding an espresso machine.

Their stated capacity of 3600 liters would allow 10 liters per day (2.6 GPD) for a year. More than you need in any home espresso machine.

Your GPD demand from an espresso machine can be roughly estimated based on how many drinks you expect to make per day. Even if you make 10 cappuccino per day, and include a liberal daily backflush it will come out to only about 0.5 GPD.

* [edit addition] After posting this I managed to come across an example of a commercial dolomite filter media, and their product does contain a significant percentage of MgO. It would more effective than simple calcite in increasing the pH because of the removal of carbonic acid / CO2 when the MgO dissolves to Mg(HCO3)2. Similar effect as Corosex media, and I think like Corosex might be prone to overcorrecting the first water from a filter that has been idle. The BWT BestMin is another example of a remin filter that reportedly uses a dolomite media.

[DeuxInfuso]

The dissolution of Ca & Mg into your RO permeate (low ion content finished output water) from a remineralizing cartridge is influenced by a few variables, such as specific cartridge minerals content, mineral form, mechanical grain size (controls water contact surface area), water pH (mostly how much CO2 is dissolved in your RO permeate), ambient temperature, and water residence time in the filter.

Naturally, different manufacturers products will have slightly different performance characteristics. All else being constant, the RO permeate input pH may have the largest role in remin cartridge dissolution kinetics. Aerated RO feedwater from a municipal supply may have less dissolved CO2, but well water is typically saturated with respect to CO2. The dissolved CO2 content affects water pH by controlling carbonic-acid content.

Dissolved CO2 easily passes through the RO membrane, but the buffering minerals, mostly bicarbonate, are rejected as "brine" in the reject stream. Thus RO finished water is generally acidic, as carbonic acid, which is the same acid we enjoy in soda pop. City water as feedwater may be somewhat less acidic if it has less dissolved CO2. Country living well water may be more acidic due to higher dissolved CO2 concentration in the RO feedwater. CO2 is derived from dissolution of atmospheric CO2, but mostly is sourced from the natural process of anaerobic mode metabolism of harmless bacteria living in soil and the subsurface in groundwater aquifer systems. If your well water has an aeration tank (not common unless you are in a high sulfate area) your permeate may be less acidic, and the remin cartridge may dissolve more slowly.

I prefer manually buffering my RO permeate (from a well water source) by adding 100 ppm potassium-bicarb, the famous Dr. Pavlis recipe, that has pH 7.5 and is entirely non-scaling. Then I don't worry about remin cartridge content, or residence time, or changing performance through time. Dr. Pavlis water also slowly dissolves any scale that may have precipitated from hard water you or a former owner may have fed your machine with, a common situation...) This is really easy to do, lots of info on these boards about this, and you never need worry about scale formation, perhaps the principal cause of machine trouble. The water tastes great, and makes great tasting espresso.

[Pressino]

I agree with both CarefreeBuzzBuzz and homeburrero's suggestions. The main reason for your considering RO is to eliminate chloride from your house water supply, and RO is the only practical way to do that for a plumbed in machine. Unfortunately you then need to add certain (ideally non-scale forming) minerals for both coffee taste and machine function (at least for machines that use boiler fill level sensors). There are really only two ways to do this: 1) Place an in-line remineralizing filter to supply the machine; or 2) Manually dissolve the minerals yourself into the water cart (or any container and use that to fill the machine's reservoir), as CarefreeBuzzBuzz suggests.

The main advantage of the cart/reservoir solution (pun intended) is that you have complete control over what you feed your machine. It is also cheaper than having to buy and plumb in a water filtration system. The disadvantage is the loss of the relative simplicity, compactness (if a cart is used rather than just the machine reservoir), and ease-of-use of a plumbed-in machine.

Those are are two choices, as I see it.