To the OP. I make R Pavlis water by mixing one gallon of distilled water with .4 grams of potassium bicarbonate....and that's it. I use a scale to weigh out the potassium bicarbonate. To me, this seems to be a much simpler way to make safe espresso machine water. Am I missing something?

Frankly, the math confuses me. I just made the concentrate described above and added 120ML of it to a 4 gallon bottle of water. I am using that water now.

When I use Third Wave Water which is a little packet of minerals to add to a gallon of distilled, I think it is more than .4 grams. I'll weigh it tonight.

B

I think either approach is valid, so use whichever you find easiest. The addition of 0.4 gram of powdered potassium bicarb to each gallon is conceptually straightforward. On some scales it's hard to hit 0.4 gram on the nose, but that's really not that important. The R Pavlis 100 mg/L potassium bicarbonate recipe would be 0.38 gram per gallon, but anything between 0.3 gram and 0.5 gram is close enough for this purpose. In terms of alkalinity measures in CaCO3 equivalents, 0.3 g/gallon would be 39 mg/L and 0.5 g/gallon would be 66 mg/L. Certainly not a difference that I could taste.

One advantage to using a concentrate is that you can get a high precision mix even with a low precision scale. In the OP's example it's easy to weigh out 32.2 grams to within a gram. Unless you're doing science that's far more precision than you need. But the big advantage to me of using a concentrate is that you only need to do the tedious part -- getting out your scale and salt and making the mix -- once every month or so. I gallon of concentrate will make over 100 gallons of coffee water, and the near daily chore of filling a reservoir can be done with shotglass to measure out the desired amount of concentrate.

blutch wrote:When I use Third Wave Water which is a little packet of minerals to add to a gallon of distilled, I think it is more than .4 grams

The TWW espresso formula's 1 gallon packet is about 1.5 gram, but over a gram of that is Epsom salt (a magnesium sulfate hydrate), and only 0.15 gram of potassium bicarbonate.

homeburrero wrote:I think either approach is valid, so use whichever you find easiest. The addition of 0.4 gram of powdered potassium bicarb to each gallon is conceptually straightforward. On some scales it's hard to hit 0.4 gram on the nose, but that's really not that important. The R Pavlis 100 mg/L potassium bicarbonate recipe would be 0.38 gram per gallon, but anything between 0.3 gram and 0.5 gram is close enough for this purpose. In terms of alkalinity measures in CaCO3 equivalents, 0.3 g/gallon would be 39 mg/L and 0.5 g/gallon would be 66 mg/L. Certainly not a difference that I could taste.

One advantage to using a concentrate is that you can get a high precision mix even with a low precision scale. In the OP's example it's easy to weigh out 32.2 grams to within a gram. Unless you're doing science that's far more precision than you need. But the big advantage to me of using a concentrate is that you only need to do the tedious part -- getting out your scale and salt and making the mix -- once every month or so. I gallon of concentrate will make over 100 gallons of coffee water, and the near daily chore of filling a reservoir can be done with shotglass to measure out the desired amount of concentrate.

The TWW espresso formula's 1 gallon packet is about 1.5 gram, but over a gram of that is Epsom salt (a magnesium sulfate hydrate), and only 0.15 gram of potassium bicarbonate.

You mentioned salt. Should I be adding salt? You also mention Epsom salt... should that be going into my concentrate? I am only adding baking soda.
B

blutch wrote:You mentioned salt. Should I be adding salt? You also mention Epsom salt

I used the term there in the general chemistry sense, to refer to any ionic mineral you might add to water. You certainly don't want to add table salt (sodium chloride) to your water. Many people believe that you may get tastier extractions with hardness minerals (calcium and/or magnesium) in the brew water, and Epsom is an easy way to get that. I think professor Pavlis would argue that you don't want the sulfate and don't need the magnesium (ground coffee is already loaded with plenty of magnesium.)

P.S.
A recent post reminded me that there is a five page thread specifically about easy ways of making the R Pavlis recipe. Here: Easiest way to make rpavlis water?