MonLon wrote:What is the TDS of your water?
How long do the filters last?
Are you happy with this solution?
Have you used other alternatives for your espresso machine/brew method? How does this one compare with them?

1) My tap water has an actual TDS of 240 ppm, and a conductivity that reads about 180 ppm on a typical TDS meter. Hardness around 135 mg/L, alkalinity around 100 mg/L, and chloride ion around 30 mg/L.

2) I get around 20 gallons out of each filter. That agrees with the ZeroWater claims for filter life: https://zerowater.com/pages/frequently-asked-questions at my TDS.

3) At my TDS, it may be cheaper to buy bottled, or better yet to refill jugs at the store's purified water (i.e., RO) dispenser, but I like the convenience of not having to lug bottles from the store. Eventually I'll probably switch to using 5 gallon (refilled) bottles and rig an under-sink water source that I can plumb in. Right now I'm short of undersink space in my kitchen.

4) I've used other methods, but this one is simple, easy, tastes good, and allows me to mix my own where I have no chloride in my espresso machine water. When brewing pourover coffee I usually just use charcoal filtered tap, which is much harder than my home-made espresso water. But I can't say that it tastes any better or worse.

P.S.
My homemade is currently a simple mix of equal mass amounts of calcium carbonate, magnesium carbonate, and potassium bicarbonate to produce a water with a total hardness of ~44 mg/L and total alkalinity of ~54 mg/L as CaCO3. That gives me water roughly similar to what they use in WBC competitions and is very easy for me to mix up. I can't say that this mix is really any better than if I were to use nothing but potassium bicarb at a similar alkalinity level.

MonLon wrote:May I ask what is the difference between the TDS and conductivity?
I thought that TDS meter is supposed to measure the TDS based on conductivity.
If this is not the case, then how do I convert the reading on my TDS meter to the actual TDS?

TDS meters measure conductivity, which is indirectly related to the amount of dissolved solids in the water. They can differ from actual TDS depending on what types of ions happen to be in the water. Most of the popular inexpensive ones, including the one that comes with ZeroWater, are calibrated against a simple NaCl (table salt) solution that gives them a conversion factor of appx 0.5, so that a conductivity of 200 micromhos/cm will indicate 100 ppm at 25C. Many TDS meters apply some temperature correction to the factor, but even with that it's best to always measure at the temp recommended in the owners manual (usually 25C = 77F).

You can calibrate them differently, and some meters allow you to easily switch between different factors. If I were to use a so-called "4-4-2" calibrated TDS meter, which has a conversion factor of about 0.65, my reading of Albuquerque water would be in close agreement with the TDS in the analysis report.

TDS meters are good enough for rough ballpark measurements, just don't take the number too seriously. For example, some folks work their recipes to hit that 150 ppm TDS number recommended by the old SCAA water standard exactly on the nose. But that measurement supposedly used a 4-4-2 calibrated meter, so it would have read more like 115 ppm on an NaCl calibrated meter like most of us are now using.

MonLon wrote:With regard to your homemade water, what ingredients and ratios do you use to get this mix?

I use powdered CaCO3, MgCO3, and KHCO3. I add about 1g of each to a 750 ml swingtop stoppered bottle for my concentrate. That concentrate is cloudy with undissolved CaCO3, so I need to shake well before using. I add a shotglass (~44ml) of that to 3L of purified water in a gallon glass jar get my brew mix. If I let that sit a while all precipitate dissolves fully - I never see precipitate in the bottom of the gallon jar. Generally on my Giotto I'm even lazier - every night I simply fill the reservoir direct from the Zerowater jug, then followup with a partial shot of my concentrate (shooting for roughly 40 ml per full reservoir tankfull.)

I'm not a true believer in this mix. It's easy for me, but I'm not convinced it's any better than simple 100 mg/L KHCO3 (rpavlis) water. Like the rpavlis water, my water has good alkalinity and zero chloride or sulfate, which appeals to my paranoia about brass and copper corrosion in my older espresso equipment.

MonLon wrote:And have you had any issues with the filters, as some people are claiming?

I've let it go too long and noticed that fishy odor. I sometimes see some resin beads or charcoal break through into the top part of the filter jug, but have never seen them down in the filtered water.