Accurate Water Testing Kits

JHCCoffee It depends on what you want to do… “high TDS” is a bit vague - you could get very high TDS and no scaling by adding say 40,000 mg/l of NaCl. I doubt you’d like coffee brewed with sea water.

Assuming you like water containing ‘general hardness’ (i.e. Ca and Mg ions, which are said to improve the taste of coffee), then avoiding scaling and corrosion is not easy at values of GH and KH that are generally used for brewing coffee. You need to choose your poison.

If you are OK without Ca and/or Mg, then adding 68 - 136 mg/l of NaHCO₃ or 80 - 160 mg/l of KHCO₃ (‘R Pavlis’ recipe) will provide 40 - 80 mg/l of alkalinity with no scaling, using very cheap chemicals that you can easily find.

My suggestion would be to try with the Pavlis / bicarbonate recipe for a couple of weeks, and seeing if you like the result in the coffee. If so, you are set - $5 of bicarbonate will last you a lifetime.

If you feel experimental, you could try a recipe with 197 mg/l of MgSO₄ · 7 H₂O (Epsom salts) and 116 mg/l of Ca citrate - this will give you something similar to the total (Mg + Ca) amount and the same KH and GH values as the TWW recipe, but without carbonates involved, so far less risk of scaling. Does it taste good? Does it scale? I don’t know, as I’ve never used it. I will make a bit of concentrate next time I need to do so (couple of weeks) and experiment with its taste. If you can wait… in the meantime try the Pavlis recipe.

JHCCoffee should I just bite the bullet and buy an RO system? If so, would I end up with a much lower TDS than 28 ppm? What TDS should I except?

The second and third questions are much easier to answer than the first one. Yes, you would expect to end up with <10 ppm TDS with a decent and well-serviced domestic RO system, probably around 1-2 ppm of dissolved minerals.

The interesting question - and part of the answer to the first one - is whether the RO water you are buying actually contains 28 ppm TDS. I doubt it - I genuinely think this is the most you could ever get, and therefore what they tell you, to avoid getting into trouble for false advertising/misdescription/breach of contract/what-have-you-in-Canadian-law.

Even assuming that it is 28ppm (of undesirable stuff), the question is the cost of the RO system vs. alternatives (e.g. ZeroWater-type filters) considering your consumption. If you are only using RO/DI water for coffee, a Zero jug is likely to be cheaper and has no installation costs vs. a domestic RO system.

JHCCoffee You don’t need to send your RO water to the lab, IMO. Please get a drop kit, measure the GH and KH of your Pure RO water on a sample of 20 ml or 40 ml for each test, multiple 17.9 by number of drops and divide the output by 4 (if 20 ml) or 8 (if 40 ml). As Rob and CoyoteOldMan advised, keep it simple.

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This is the TWW espresso recipe quoted above if you put it into an imperial gallon of water. TWW want you to put it in a US gallon which is about 20% less water.

There’s no accounting for the sodium from the TWW sachets as their listed ingredients are Magnesium Sulphate, Calcium Citrate, and Potassium Bicarbonate. It looks like the amounts have been tweaked slightly, maybe they realised they get alkalinity from citrate and sulphate (not calculated) and reduced the bicarbonate by almost 50%.

It might be worth just using Calcium citrate and Magnesium Sulphate to remineralise some water and then titrate the sample down to a pH of 4.5. Citrate provides alkalinity below this but as it’s acidic I think that’s missing the point when it comes to making coffee and taking care of machines.

So where the Na and Cl come from in your analysis? Likely the RO water itself. Possibly put through a salt softener before RO giving it high Na and Cl slipping through is normal.